The UN envoy for Syria, Staffan de Mistura, was in Riyadh Tuesday for talks with diplomats and Syrian opposition representatives on efforts to end the nearly five-year war, an Arab source said.
His visit comes amid heightened tensions between Saudi Arabia, the main Sunni power in the region, and Shiite-dominated Iran over Riyadh's execution of a prominent Shiite cleric and dissident.
There are concerns that the row could derail growing efforts to end the conflict, as Riyadh backs rebels fighting to overthrow President Bashar al-Assad and Iran supports the Syrian president's regime.
De Mistura is also expected in Iran later this week and in Damascus on Saturday, according to UN sources.