Saudi Arabia is to host a meeting of the Syrian opposition later this month as the United Nations prepares to convene new peace talks with the government buoyed by victories over the Islamic State group.
The meeting will be held in Riyadh from November 22 to 24 at the request of opposition factions and will aim to form a "joint negotiating delegation to resume direct negotiations in Geneva under the auspices of the UN," the official Saudi Press Agency reported late on Monday.
The latest round of UN-brokered peace talks is due to open on November 28. UN envoy Staffan de Mistura said late last month that the talks had reached a "moment of truth".
The government has been buoyed by its recapture from the Islamic State (IS) militant group of the eastern city of Deir Ezzor and other towns further down the Euphrates Valley towards the Iraqi border.
The opposition has been weakened by the capture of most of the northwestern province of Idlib by a Islamist militant-led alliance which is excluded from the Geneva talks.
Late on Monday, US Defence Secretary Jim Mattis voiced strong support for the peace process, vowing that the coalition Washington has led against Islamist militant groups in Syria and Iraq would remain committed to the search for a lasting political solution.
"We're not just going to walk away right now until the Geneva process has traction," Mattis told reporters.
"We are going to make sure we set the conditions for a diplomatic solution."
This year, the Geneva talks have been largely sidelined by a separate talks process in the Kazakh capital Astana sponsored by rebel supporter Turkey and government allies Iran and Russia.
Those talks have resulted in the establishment of three safe zones in key battlegrounds between the government and the rebels, and plans for a fourth.