Yemen's Iran-backed Huthi rebels said on Sunday they had seized an Israeli ship in the Red Sea, a claim immediately denied by Israel.
The allegation came days after the rebel group had threatened to target Israeli vessels in the Red Sea over Israel's war with Hamas in the Gaza Strip.
"We took an Israeli cargo ship to the Yemeni coast," an unidentified Huthi official said in a statement, adding that further details would be released later.
A Yemeni maritime source said the Huthis "seized a commercial vessel" and took it to the port of Salif in the coastal city of Hodeida which the rebels control, without specifying its nationality.
Israel's military denied the ship was Israeli.
A statement by the army on X, formerly Twitter, said: "The hijacking of a cargo ship by the Huthis near Yemen in the southern Red Sea is a very grave incident of global consequence."
"The ship departed Turkey on its way to India, staffed by civilians of various nationalities, not including Israelis.
"It is not an Israeli ship," the Israeli army said in the statement.
The office of Israeli Prime Minister Benjamin Netanyahu also denied the ship was Israeli but denounced, in a statement, "the Iranian attack against an international vessel".
"The ship, which is owned by a British company and is operated by a Japanese firm, was hijacked with Iran guidance by the Yemenite Huthi militia," it said.
"Onboard the vessel are 25 crew members of various nationalities including Ukrainian, Bulgarian, Filipino and Mexican," it added.
- Vital shipping route -
On November 14, Huthi rebel leader Abdul Malik al-Huthi said the group was on the lookout for Israeli vessels in the commercially vital waters of the Red Sea -- even those that do not have Israeli flags.
"Our eyes are open to constant monitoring and searching for any Israeli ship," he said in a speech broadcast by the rebels' Al-Masirah TV station.
"The enemy relies on camouflage in its movement in the Red Sea, especially in Bab al-Mandab (strait), and did not dare to raise Israeli flags on its ships... and turned off identification devices."
"We will search and verify the ships that belong to him, and we will not hesitate to target them, and let everyone know that he is afraid," he added.
The Bab al-Mandab Strait is the narrow pass between Yemen and Djibouti at the foot of the Red Sea, one of the world's busiest shipping lanes, which carries about a fifth of global oil consumption.
The Huthis, declaring themselves part of the "axis of resistance" of Iran-affiliated groups, have launched a series of drone and missile strikes targeting Israel since October, following an unprecedented attack by Hamas militants on Israel.
Israel has vowed to destroy Hamas, which controls the Gaza Strip, after the Palestinian militants killed around 1,200 people and took about 240 hostages on October 7, according to Israeli authorities.
The Hamas government in Gaza says 12,300 have been killed in Israel's relentless aerial bombardment and ground operations in the territory in retaliation.