Saudi Arabia's ambassador to Iran arrived Tuesday in the Islamic Republic, and his counterpart landed in Riyadh, cementing a restoration of ties between the Gulf rivals after a seven-year rupture in ties.

Shiite-dominated Iran and Sunni Muslim Saudi Arabia agreed to resume diplomatic relations and reopen their respective embassies following a China-brokered deal announced in March.

Riyadh and Tehran severed ties in 2016 after Saudi diplomatic missions in Iran were attacked during protests over Riyadh's execution of Shiite cleric Nimr al-Nimr.

Saudi Arabia's leadership recognises the "importance of strengthening ties, increasing engagement... and taking the (relationship) to broader horizons," ambassador Abdullah Alanazi said upon his arrival in Tehran to take up his duties, according to a Saudi Foreign Ministry statement.

Also on Tuesday, Iran's ambassador to Saudi Arabia, Alireza Enayati, arrived in the capital Riyadh where he was received by foreign ministry officials and embassy staff, according to Iran's official IRNA news agency.

Alanazi was formerly Saudi Arabia's ambassador to Oman, while Enyati was previously Iran's Kuwait envoy.

Saudi Arabia's embassy in Tehran resumed operations last month. In June, Iran marked the reopening of its embassy in Riyadh with a flag-raising ceremony.

Last month Iran's top diplomat, Foreign Minister Hossein Amir-Abdollahian, preached unity and dialogue during his first visit to Saudi Arabia since the surprise rapprochement was announced, saying bilateral ties were "progressing in the right direction".

Iran and Saudi Arabia have backed opposing sides in conflict zones across the Middle East for years.

Since the March deal, Saudi Arabia has restored ties with Iranian ally Syria and ramped up a push for peace in Yemen, where it has for years led a military coalition against the Iran-backed Huthi forces.