Discussions on Iran and Syria will dominate the Arab League's annual summit onn Sunday, when Arab leaders, excluding Syrian President Bashar al-Assad, will meet in the Saudi city of Dahran.
Saudi Arabia is expected to push for a tough, unified stance against its regional arch-rival Iran at the meetng.
The two regional titans, locked in proxy wars in Syria and in Saudi Arabia's southern neighbour Yemen, also back opposing parties in Iraq and Lebanon.
The summit begins 24 hours after the United States, France and Britain launched controversial air strikes in war-torn Syria in response to a reported regime chemical attack on the decimated rebel enclave of Eastern Ghouta last week.
Summits of the Arab League, established in 1945, rarely result in action.
The last time the bloc made a concrete move was in 2011, when it suspended Syria's membership over the Assad regime's role in the war.
Syria remains suspended from the organisation.
Saudi Arabia's King Salman will chair Sunday's summit in the eastern city of Dhahran, home to Saudi Arabia's oil giant Aramco and 160 kilometres (100 miles) across the Gulf from Iran.
Syria's war, the most complex of the region's conflicts, is the main point of contention pitting Riyadh and its allies, who mainly back Sunni rebels, against regime backer Iran and its Lebanese ally Hizballah.
Saudi Arabia on Saturday declared its full support for US-led air raids on Syria, which the Pentagon said had "successfully hit every target".
Qatar, which has confirmed it will attend the summit, also backed the strikes.
Its foreign ministry tweeted support for "operations against specific military targets used by Syrian regime in its chemical attacks".
Gulf Arab states have made massive donations to Syria but have not officially offered asylum to Syrians.
Despite widespread Arab condemnation of the suspected chemical attack, the Dhahran summit is unlikely to call for Assad to step down.
Seven years into a war that has claimed hundreds of thousands of lives, Saudi Arabia and Iran now agree that the country's future cannot be decided solely by the Assad regime, whose troops have regained the upper hand with massive support from Russia.
Saudi Arabia's powerful Crown Prince Mohammed bin Salman, 32-year-old son of the king and de facto ruler of the world's largest exporter of oil, has said Assad will stay.