All members of the main Syrian opposition will leave peace talks in Geneva by Friday, a source close to the High Negotiations Committee (HNC) and a Western diplomat said on Thursday.
"All members of the HNC will be leaving today and tomorrow," the source told Reuters on Thursday, declining to be identified.
The diplomat, speaking on condition of anonymity, said the delegation had been given instructions by chief coordinator Riad Hijab to leave the talks by Friday.
"I'm saddened and believe it's a mistake," the diplomat said. "It will be very difficult to find a pretext for them to return given the situation on the ground and now the regime knows that a bombing will ensure they stay away."
The diplomat said efforts were still being made to convince officials to remain in Geneva, but it appeared unlikely to happen.
The HNC, which is backed by Western nations, key Arab states including Saudi Arabia, and Turkey, had paused its representation in the talks on Monday, but agreed to continue technical talks away from the United Nations building.
It said it could not continue given the deteriorating military situation on the ground, lack of progress on humanitarian issues and complete blockage in discussing the release of thousands of prisoners.
Declining to take questions on the state of the talks, U.N. special envoy Staffan de Mistura told reporters he would outline where the process stood on Friday.
"If humanitarian aid increases as it should and the cessation of hostilities goes back into what we consider a hopeful mood, that would help certainly help political discussion," he said.