GENEVA: Syria's warring sides were meeting in Geneva Saturday in a last-ditch effort to save deadlocked peace talks amid fears that they could collapse altogether.
The second round of talks appeared close to fizzling out on Friday, but UN mediator Lakhdar Brahimi at the last moment invited the two sides to come back for a final joint meeting Saturday morning.
After days of discussions, the rivals stood further apart than ever, seeming to agree on only one thing: that the negotiations were going nowhere.
"We deeply regret that this round did not make any progress," Syrian Deputy Foreign Minister Faisal Muqdad said after meeting Brahimi on Friday.
Opposition spokesman Louay Safi agreed: "The negotiations have reached an impasse."
As the parties in Geneva failed to agree even on an agenda for their talks, the death toll mounted in Syria, where more than 136,000 people have been killed in three years.
A monitoring group this week that more than 5,000 people had been killed since a first round of talks began on January 22.
The United Nations warned Friday that more than 2,700 refugees had poured across the Lebanese border as the Syrian army carries out an offensive in the Qalamun mountains and heads towards the opposition-held town of Yabrud.
Thousands had already fled the town, but as many as 50,000 people were believed to still be inside.
Washington expressed outrage at the aerial bombings and siege of the city.
"We again call on all members of the international community, including Assad's allies, to make clear to the regime that it must immediately cease these unwarranted attacks that undermine the Geneva process and the prospects of peace in Syria," State Department spokesman Edgar Vasquez said.
In Geneva, the second round of talks, which began Monday, appeared set to wrap up Saturday with no sign of progress and it was unclear if Brahimi could convince the foes to come back for a third round of negotiations.
Washington, which backs the opposition and initiated the so-called Geneva II talks with regime ally Russia, voiced deep frustration Friday at the stalemate.
"Talks for show make no sense," a senior US official said Friday.
US President Barack Obama vowed to push the regime harder.
"There will be some intermediate steps that we can take to apply more pressure to the Assad regime," he said after talks with Jordanian King Abdullah II in California, but did not specify what such steps might be.
In an effort to inject life into the talks, both the United States and Russia sent top envoys to Geneva this week to meet Brahimi and the two sides.
But after a meeting with high-ranking US and Russian diplomats Thursday, the veteran peacemaker admitted that "failure is still staring us in the face".
Washington blamed the impasse squarely on the Syrian regime, and chastised Moscow for not doing enough to push its ally to engage "seriously" in the process.
Regime representatives have so far refused to discuss anything beyond the "terrorism" it blames on its opponents and their foreign backers, and stubbornly insist President Bashar al-Assad's position is non-negotiable.
They have declined to discuss the opposition coalition's 24-point proposal for a political transition, or to consider Brahimi's suggestion that the parties discuss the two issues in parallel.
Observers said the talks were hanging in the balance.
"We are in a dead end," said a Western diplomat, warning prospects looked "grim" and that it would be tough for Brahimi to organise a third round.
Spokesman Safi said the opposition was appealing to the international community to "make a difference to push this process forward" but that a "pause" looked likely in the meantime.
Algerian veteran peacemaker Brahimi, who helped broker past deals in Lebanon, Afghanistan and Iraq, has pledged not to "leave one stone unturned if there is a possibility to move forward".
But the Western diplomat cautioned: "I would not assume he will stay indefinitely," saying Brahimi might have "concerns about his own credibility" if he allows the process to continue like a broken record.
The ongoing evacuation of civilians from besieged rebel-held areas of Homs -- seen as the only tangible result so far of the Geneva II talks -- has been hailed as a relative success.
But UN humanitarian chief Valerie Amos expressed frustration at the "extremely limited and painstakingly slow" process of getting 1,400 people out, given that 250,000 are under siege across Syria.
Syria's deputy foreign minister Muqdad had sharp words for Amos, accusing her of an "unacceptable" failure to recognise there was "terrorism" in Syria and that it hindered aid operations.