Iran and Saudi Arabia will start formal talks next week to resume direct scheduled flights between Tehran and Riyadh and other cities, an Iranian official told the state-affiliated news agency ILNA on Sunday.

Regular flights would be another step towards restoring ties between the two Middle Eastern rivals. A Chinese-mediated agreement in March restored diplomatic relations after years of tension that threatened the security of the entire region and fuelled conflicts in Iraq, Syria and Yemen.

"There are no restrictions regarding the launch of direct flights from Tehran to Riyadh, or other cities," Deputy Minister of Roads and Urban Development Mohammad Mohammadibakhsh said, according to ILNA.

"A bilateral working group will start final negotiations next week to have non-haj flights between the two countries," he said, referring to the annual Muslim pilgrimage to the holy city of Mecca in Saudi Arabia.

Shi'ite-dominated Iran and Sunni Gulf monarchy Saudi Arabia cut ties in 2016 over Saudi Arabia's execution of a Shi'ite Muslim cleric and the subsequent storming of Riyadh's embassy in Tehran.

There have been no regular direct flights between the two countries for years. Currently, only occasional direct flights take off from Iran carrying haj pilgrims.

Mohammadibakhsh said a resumption of flights would include travel for pilgrims of the year-round Umrah - which can be undertaken at any time year - and also non-religious travel.

Iran had already presented a list of airline companies which might operate flights, he said, but did not specify any.

The Saudi Arabian government did not immediately respond to a request for comment.

(Reporting by Dubai Newsroom, Editing by Louise Heavens)