THE first Syria peace talks for two years were a “complete failure” before they started yesterday, a Western diplomat said, after the United Nations announced it would press ahead with them despite an opposition boycott.

Opponents of President Bashar al-Assad said they were far more concerned with fending off a Russian-backed military onslaught, with civilians reported to be fleeing as the Syrian army and allied militia tried to capture a suburb of Damascus and finish off rebels defending it.

UN envoy Staffan de Mistura has invited the Syrian government and an opposition umbrella group to Geneva for “proximity talks”, in which they would meet in separate rooms.

But so far the main opposition High Negotiations Committee (HNC) has refused to attend, insisting it wanted an end to air strikes and sieges of towns before talks can start.

The boycott defies Washington, which has urged the opposition to take up the “historic opportunity” for the talks, without preconditions.

A UN statement said de Mistura would open the talks as scheduled by meeting the government delegation headed by Syria’s ambassador to the United Nations. Meetings with “other participants” would take place “subsequently” it said.

“It is a complete failure,” said a Western diplomat, on condition of anonymity, describing the event as a boon for Assad’s government.

“They are completely off the hook. With whom are they going to talk? If you want to engage in negotiations, you have to have a partner.

“It’s a wonderful occasion for the regime to show they are willing.”

If opposition members do attend “they will be telling you they are coming in their personal capacity,” the diplomat said.

On Thursday the opposition HNC, which groups both armed and political opponents of Assad and has been meeting in Riyadh this week, said it would not attend the start of talks yesterday because it had not received convincing answers over its demand for goodwill steps such as a ceasefire.

Another major force, the Kurds who control much of north east Syria and have proven one of the few groups capable of winning territory from Daesh, were excluded from the talks after Turkey demanded they be kept away. The Kurds say their absence means the talks are doomed to fail.

International diplomacy has so far seen only failures in a five-year-old multi-sided ethno-sectarian civil war that has killed more than 250,000 people and driven more than 10 million from their homes while drawing in regional states and global powers.

De Mistura’s two predecessors both quit in apparent frustration after staging failed peace conferences.

Since the last talks collapsed in 2014, Daesh fighters surged across Syria and Iraq, declaring a “caliphate”. The United States and its European and Arab allies launched air strikes against them and Russia joined in last year with a separate air campaign to support Assad.

Moscow’s intervention in particular has altered the balance of power on the ground, giving strong momentum to government forces and reversing months of rebel gains.

The Syrian military and allied militia are seeking to build on gains in western Syria, and have turned their focus to opposition-held suburbs south west of Damascus.

The aim is to crush rebels in the district of Daraya to secure the nearby military airport at Mezzeh, said Rami Abdulrahman, director of the Syrian Observatory for Human Rights.

Rebels had rejected a government deadline for them to withdraw from the suburb of Mouadamiya – home to 45,000 people – by yesterday, said Abu Ghiath al-Shami, spokesman for rebel group Alwiyat Seif al-Sham.