Bahrain and Sudan joined Saudi Arabia in severing diplomatic relations with Iran on Monday as the worst crisis in three decades between the region's rival Sunni and Shiite powers drew worldwide expressions of alarm.
Russia offered to mediate, the United Nations dispatched a senior envoy for crisis talks in Riyadh and Tehran, and a growing list of nations expressed concern at the implications of the rupture - touched off by Saudi Arabia's execution of a prominent Shiite cleric as part of its largest mass execution of prisoners in more than 35 years.
Iran said Saudi Arabia made a "strategic mistake" that could only further divide the region and fuel militancy during crucial battles against the Islamic State and efforts to end Syria's civil war.
The Persian Gulf nation of Bahrain - a close Saudi ally and home to the U.S. Navy's 5th Fleet - ordered Iranian diplomats to leave within 48 hours.