Iranian state media said President Ebrahim Raisi and his foreign minister died on Monday after their helicopter crashed in a mountainous region of the country.
The government has not yet issued a confirmation of the leader's death.
Rescue teams had been scouring the area since Sunday afternoon after a helicopter carrying Raisi, Foreign Minister Hossein Amir-Abdollahian and other officials had gone missing.
Early Monday, relief workers located the missing helicopter, with state TV saying the president had died.
"The servant of Iranian nation, Ayatollah Ebrahim Raisi has achieved the highest level of martyrdom whilst serving the people," state television said Monday, with Mehr news agency also saying he was dead.
State television broadcast photos of Raisi, with the voice of a man reciting the Koran playing in the background.
Iran's vice president for executive affairs Mohsen Mansouri posted on X a Koranic verse used to express condolences.
Supreme leader Ayatollah Ali Khamenei, who has ultimate authority in Iran, declared five days of mourning and assigned vice president Mohammad Mokhber, 68, to assume interim duties ahead of elections within 50 days.
- Ultraconservative -
Fears had been growing for the 63-year-old ultraconservative after contact was lost with the helicopter carrying him as well as Foreign Minister Hossein Amir-Abdollahian and others in East Azerbaijan province on Sunday.
A total of nine people were on board the aircraft, according to Tasnim news agency.
Iran's Red Crescent chief Pirhossein Koolivand said rescue teams headed towards the site of the crash after locating the aircraft.
"The helicopter has been found. Now, we are moving toward the helicopter," said Koolivand. "We are seeing the helicopter. The situation is not good."
"Upon finding the helicopter, there was no sign of the helicopter passengers being alive as of yet," state TV reported about 15 hours after the aircraft went missing.
Iranian media including Fars news agency shared drone images of what appeared to be the wreckage of the helicopter.
State TV first reported Sunday afternoon that "an accident happened to the helicopter carrying the president" in the Jolfa region of East Azerbaijan province.
Interior Minister Ahmad Vahidi said the helicopter "made a hard landing" in bad weather. He urged people to get their information "only from state television", and not listen to foreign media channels Iran deems hostile to the Islamic republic.
Raisi's convoy had included three helicopters, and the other two had "reached their destination safely", said the Tasnim news agency.
Supreme leader Ayatollah Ali Khamenei urged Iranians to "not worry" about the leadership of the Islamic republic, saying "there will be no disruption in the country's work".
Expressions of concern and offers of help came from abroad, including Iraq, Kuwait, Qatar, Saudi Arabia, Syria, Russia, China and Turkey, as well as from the European Union which activated its rapid response mapping service to aid in the search effort.
- Massive search effort -
Iran's cabinet held an emergency meeting led by Vice President Mohammad Mokhber after the incident, the IRNA news agency reported.
Army, Revolutionary Guard and police officers were involved in the search, authorities said, as TV stations showed pictures of Red Crescent teams walking up a hill in the mist, while rows of emergency response vehicles waited.
Raisi had visited the northwestern province to inaugurate a dam project together with Azerbaijan's President Ilham Aliyev, on their common border.
Aliyev said in a post on X that "we were profoundly troubled by the news of a helicopter carrying the top delegation crash-landing in Iran".
Foreign countries were closely following the search at a time of high regional tensions over the Gaza war between Israel and Hamas since October 7 that has drawn in other armed groups in the Middle East.
A US State Department spokesman said: "We are closely following reports of a possible hard landing of a helicopter in Iran carrying the Iranian president and foreign minister", adding that "we have no further comment at this time".
US President Joe Biden has been briefed on the crash, an American official said on condition of anonymity.
- 'Servant of the people' -
Raisi has been president since 2021 when he succeeded the moderate Hassan Rouhani, at a time when the economy was battered by US sanctions over Iran's contested nuclear programme.
Iran saw a wave of protests triggered by the death in custody of Iranian-Kurdish woman Mahsa Amini in September 2022 after her arrest for allegedly flouting dress rules for women.
In March 2023, regional rivals Iran and Saudi Arabia signed a surprise deal that restored diplomatic relations.
The Gaza war sent regional tensions soaring and a series of tit-for-tat escalations led to Tehran launching hundreds of missiles and rockets directly at Israel in April this year.
In a speech following Sunday's dam inauguration, Raisi emphasised Iran's support for Palestinians, a centrepiece of its foreign policy since the 1979 Islamic revolution.
"We believe that Palestine is the first issue of the Muslim world, and we are convinced that the people of Iran and Azerbaijan always support the people of Palestine and Gaza and hate the Zionist regime," said Raisi.
Hamas, which the United States and European Union consider a terrorist group, said that "in this painful incident, we express our full solidarity with the Islamic Republic of Iran, its leadership, government and people".
https://www.youtube.com/watch?v=TjigjwS9Hg4
A president close to supreme leader
Always piously dressed in a black turban and religious robe, Iran's ultraconservative President Ebrahim Raisi took office during a tumultuous period of confrontation abroad and mass protest at home.
On Monday, the 63-year-old president was declared dead after his helicopter crashed a day earlier in a remote and fog-shrouded western mountain region while travelling back from East Azerbaijan province where he had inaugurated a dam project.
After the news of his death, state television showed photos of Raisi with the voice of a man reciting the Koran in the background and footage of faithful praying in Raisi's home city.
Search and rescue operations went on for more than 15 hours after the crash, before the site was found and Raisi's body was retrieved along with others who had died with him.
The Iranian president -- whose career started in the years after the 1979 Islamic revolution and who is close to supreme leader Ayatollah Ali Khamenei -- took power in a 2021 election that was followed by turbulent years of protests and tensions.
Like Khamenei, Raisi has often spoken up defiantly as Iran, the biggest Shiite Muslim power, has been in a tense standoff with its declared arch foes the United States and Israel.
Raisi took power after an election in which more than half the electorate stayed away and several political heavyweights had been barred from standing.
He succeeded the moderate Hassan Rouhani, whose signature achievement was a 2015 nuclear deal with world powers that gave Iran relief from international sanctions.
Like other ultraconservatives, Raisi harshly criticised his predecessor's camp after then-president Donald Trump unilaterally withdrew the United States from the nuclear pact in 2018 and reimposed punishing sanctions on Iran.
Raisi took the reins of a country in social and economic crisis.
After portraying himself as a corruption-fighting champion of the poor, Raisi announced austerity measures that caused a sharp increase in the price of some staples, triggering anger at the high cost of living.
Then, in late 2022, a wave of nationwide protests erupted following the death in custody of Mahsa Amini after her arrest for allegedly breaching Iran's strict Islamic dress code for women.
In a landmark event in March 2023, Iran and Saudi Arabia, long-time regional foes, announced a surprise deal that restored diplomatic relations.
But the Gaza war that broke out on October 7 between Israel and Hamas sent regional tensions soaring again, and tit-for-tat escalations led to Tehran launching hundreds of missiles and rockets directly at Israel last month.
Earlier on Sunday, Raisi emphasised Iran's support for the Palestinians -- a centrepiece of the country's foreign policy since the Islamic revolution -- declaring that "Palestine is the first issue of the Muslim world".
- Head of judiciary -
Born in 1960 in the northeastern holy city of Mashhad, Raisi as young man, with a salt-and-pepper beard and thin glasses, studied theology and Islamic jurisprudence under Khamenei.
He married Jamileh Alamolhoda, an educational sciences lecturer at Tehran's Shahid-Beheshti University. They have two daughters.
Aged just 20, in the wake of the Islamic revolution that toppled the US-backed monarchy, Raisi was named prosecutor-general of Karaj next to Tehran.
He served as Tehran's prosecutor-general from 1989 to 1994, deputy chief of the Judicial Authority for a decade from 2004, and then national prosecutor-general in 2014.
In 2016, Khamenei put Raisi in charge of a charitable foundation that manages the revered Imam Reza shrine in Mashhad and controls a large industrial and property asset portfolio.
Three years later, the supreme leader appointed him head of the Judicial Authority, and Raisi was also a member of the assembly of experts that selects the supreme leader.
His black turban signifies direct descent from Islam's Prophet Mohammed, and a few months after he became president, Iranian media started referring to him by the title of ayatollah in the Shiite clerical hierarchy.
Raisi has been on Washington's sanctions blacklist for complicity in "serious human rights violations" -- charges rejected as null and void by the authorities in Tehran.
For Iran's exiled opposition and human rights groups, his name is a reminder of the mass executions of Marxists and other leftists in 1988, when Raisi was deputy prosecutor of the Revolutionary Court in Tehran.
Asked in 2018 and again in 2020 about the executions, Raisi denied playing a role, even as he lauded an order he said was handed down by the Islamic republic's founder Ayatollah Ruhollah Khomeini to proceed with the purge.
When the "Green Movement" in 2009 rallied against populist president Mahmoud Ahmadinejad's winning a disputed second term, Raisi was uncompromising.
"To those who speak of 'Islamic compassion and forgiveness', we respond: We will continue to confront the rioters until the end and we will uproot this sedition," he pledged.
Abdollahian – a career diplomat
Iranian Foreign Minister Hossein Amir-Abdollahian, who died in a helicopter crash along with President Ebrahim Raisi, was known for his fierce anti-Israel sentiment and scepticism of the West.
A career diplomat and conservative figure with close ties to the Revolutionary Guards, Amir-Abdollahian took office following Raisi's 2021 election win.
State media at the time hailed his support for "the Axis of Resistance" of Tehran-aligned armed groups across the Middle East arrayed against arch-foe Israel.
Amir-Abdollahian's tenure as Iran's top diplomat was marked by intense diplomatic efforts aiming to end Iran's isolation and offset the impact of crippling US sanctions over Iran's contested nuclear programme.
He particularly sought to forge relations with the Islamic republic's Arab neighbours including the region's Sunni Muslim powerhouse Saudi Arabia.
In a landmark Chinese-brokered deal, Tehran and Riyadh agreed in March 2023 to restore ties and reopen their respective embassies after a long rift.
Amir-Abdollahian was born in the city of Damghan, east of Tehran, in 1964. He was married and had two children.
He had earned a bachelor's degree in international relations from the University of Tehran in 1991, later completing a master's degree and a doctorate in the same field.
As a diplomat in the Iranian foreign service, his postings included Iraq, from 1997 to 2001, and Bahrain, from 2007 to 2010.
Under former populist president Mahmoud Ahmadinejad, Amir-Abdollahian served as deputy foreign minister for Arab and African affairs.
He was involved in efforts to restart stalled negotiations on Iran's nuclear programme, after a 2015 deal with Western governments unravelled as the United States unilaterally withdrew from the accord in 2018 under then president Donald Trump.
Talks however have ground to a standstill.
- Close to Revolutionary Guards -
Throughout his career, Amir-Abdollahian was known for his strong ties to the Islamic Revolutionary Guard Corps (IRGC), the ideological arm of Iran's military.
The diplomat was particularly close to the revered IRGC general Qasem Soleimani, the commander of its foreign operations arm who was killed in a 2020 US drone strike in Baghdad.
Amir-Abdollahian had hailed Soleimani's "strategic genius" and in a June 2020 interview called him a "true diplomat" for his negotiation skills.
Last month, with regional tensions soaring over the ongoing Gaza war and with violence drawing in regional Iranian allies, Amir-Abdollahian defended Tehran's first-ever direct attack on sworn enemy Israel.
The Iranian attack was in retaliation for an earlier air strike widely blamed on Israel that levelled Tehran's Damascus consulate and killed seven Revolutionary Guards, two of them generals.
Amir-Abdollahian explained the attack to be "in the framework of legitimate defence and international law".
He later downplayed a reported retaliatory Israeli raid on Iran's central province of Isfahan, home to a key nuclear facility, saying it was akin to child's play.