Thousands of civilians and fighters in four besieged Sunni and Shia towns are being evacuated in a deal brokered by Qatar and Iran. Separately, France's foreign minister says Assad comments denying the Idlib chemical attack were "100% lies."
The transfer of the populations of two majority Shia Syrian towns, in exchange for moving Sunni opposition fighters and civilians out of two others, has started, under an evacuation deal between warring parties, a monitor said on Friday.
The British-based Syrian Observatory for Human Rights said buses carrying residents departed from the predominantly Shia towns of Foua and Kefraya, long besieged by the opposition in northwestern Idlib province, but had not yet crossed into regime-held territory.
Buses carrying mostly Sunni opposition and their families simultaneously left the town of regime-besieged Madaya near Damascus, but were still passing through regime-held areas, the Observatory said.
It said the evacuation of Zabadani, also besieged by the regime, had been delayed until the evening or early Saturday, without elaborating.
A member of one of the Shia parties earlier said 60 buses were moving through the town of Foua.
A similar number of buses were leaving Madaya, the Observatory said.
Bashar al Assad's regime has struck a number deals in the past year which have provided for rebels and their families to leave areas the opposition has held, often after months or years of being besieged by regime forces.
The opposition says the deals amount to forced population transfer and deliberate demographic change.
The armed opposition fighting for six years to unseat Assad is mostly Sunni Muslim, like most of Syria's population. Assad is from the Alawite religious minority, and is supported by Shia fighters from Iran and the Lebanese Hezbollah group.
France says Assad is lying about the Idlib chemical attack
French Foreign Minister Jean-Marc Ayrault on Friday dismissed as "100 percent lies" comments by Assad a day earlier that a poison gas attack blamed on his government last week in Idlib province was "100 percent fabrication."
British scientists at the Organisation for the Prohibition of Chemical Weapons (OPCW) in The Hague on Thursday confirmed earlier testing by Turkish authorities that found that sarin gas was used in the attack on Khan Shaykhun, which killed more than 80 people and wounded at least 550 others.