On the eve of the talks, Riyadh blasted what it called Iranian "interference" in the region and demanded "firmness" over attacks on Gulf oil tankers and pipelines.

The call came just hours after US National Security Advisor John Bolton said Iran was almost certainly behind the sabotage of four ships, including two Saudi oil tankers, off the UAE coast.

Iran-aligned Yemeni rebels meanwhile have stepped up drone attacks on the kingdom -- one of which resulted in the temporary shutdown of a major oil pipeline.

Saudi Arabia, a staunch US ally, was getting ready to welcome leaders from across the Arab and Muslim world for emergency Gulf and Arab summits and a meeting of the heads of state of Islamic nations.

Riyadh called the talks to discuss the standoff with Iran and ways to isolate Tehran amid fears of a military confrontation.