Iran on Friday called on Saudi Arabia to release one of its nationals arrested during the hajj pilgrimage, as the two regional rivals engage in talks to mend severed relations.

The Islamic republic revealed the arrest in a foreign ministry statement about a phone call between Foreign Minister Hossein Amir-Abdollahian and his Iraqi counterpart Fuad Hussein.

Iraq has been mediating the talks between its two neighbours since April last year.

"In this call, Iran's foreign minister followed up on the fate of an Iranian national arrested in Saudi Arabia during the hajj pilgrimage and called (on the Iraqi FM) to convey a message for their release," the statement said.

It did not provide further details on the identity of the citizen or the reason for the detention during the hajj annual Muslim pilgrimage last month.

Nearly 780,000 pilgrims from abroad attended this year's hajj, according to Saudi officials.

Regional rivals Tehran and Riyadh have had no relations since 2016 when Iranian protesters attacked Saudi diplomatic missions in Iran after the kingdom executed Shiite cleric Nimr al-Nimr.

Iraq has hosted five rounds of talks between Sunni Muslim Saudi Arabia and Shiite-majority Iran, which support opposing sides in various conflicts around the region.

Amir-Abdollahian said last month that his country and Saudi Arabia were ready to move talks to a higher level, in the political and public spheres, after earlier rounds mainly at the level of security officials.

Iraq's foreign minister said on July 23 that his country was preparing to host a "public" meeting of his Saudi and Iranian counterparts.