Little progress towards breaking the deadlock was apparent, despite appeals from UN-Arab League mediator Lakhdar Brahimi to end the “nightmare” of the Syrian people.

The veteran peacemaker was downbeat after a three-hour session Tuesday marking the first face-to-face talks between Syria's rival camps this month.

“The beginning of this week is as laborious as it was the first week,” Brahimi told reporters.

“We are not making much progress.”

The current round of talks is set to last until Friday.

But it got off to a shaky start on Monday, and Tuesday's session did not appear to achieve anything beyond a restating of well-known positions.

“I think Geneva under the current circumstances will end in failure,” Ali Haidar, Syria's reconciliation minister, told AFP in Damascus.

Opposition spokesman Louay Safi said his side would not “run away”, but that without progress it would be “more honest to say we have failed”.

A first round was held in Geneva from January 24-31, when the simple fact of getting the foes to the table for the first time since the war erupted in 2011 was deemed a breakthrough.

But neither has budged an inch.

The opposition says the only way to end the conflict is to form a transitional government – without President Bashar al-Assad.

The regime insists Assad's future is non-negotiable and that the talks must focus on halting “terrorism” – its term for a revolt it says is fuelled by foreign jihadists and Gulf money.

In Geneva, key Assad aide Buthaina Shaaban blasted the opposition for refusing to “acknowledge that there is terrorism in Syria”.

“The only thing they want to discuss is the transitional government,” she told AFP.

The opposition, which notes that the mainstream Free Syrian Army rebels are themselves fighting the jihadists, rejects the broadbrush terror label applied by the regime.

It wants discussions to address regime actions such as starving out opposition-held areas and raining explosives-packed “barrel bombs” from helicopters.

The war, which began after a regime crackdown on Arab Spring-inspired protests in March 2011, has now claimed more than 136,000 lives, sent millions fleeing their homes, sparked a humanitarian catastrophe and put massive strain on refugee-hosting neighbours Turkey, Lebanon, Jordan and Iraq.