UN-brokered talks aimed at ending Syria's brutal conflict will push ahead until April 27, despite the departure of the main opposition group, a negotiator in the talks said on Friday.

Syria's main opposition High Negotiations Committee (HNC) earlier this week halted its formal participation in the round of talks that began in Geneva on April 13 in frustration over surging violence on the ground.

But another opposition group close to Moscow, which is deemed more acceptable by the Syrian government, said it would remain in the Swiss city through next Wednesday and expected to meet with UN mediator Staffan de Mistura after the weekend.

"We will continue the talks until April 27, according to the initial invitation we received from de Mistura," Qadri Jamil, co-president of the so-called Moscow Group and Syria's former deputy premier, told AFP.

"We are continuing to communicate with the UN and we will meet Mr de Mistura at the beginning of next week to continue discussing our vision with him," he said, speaking in Arabic.

He said there was no reason to halt the talks over the departure of the HNC, an umbrella group comprising the main Syrian opposition and rebel factions that came together in Riyadh in December.

"The Riyadh delegation is one of the delegations participating in Geneva, and the idea that this delegation is the chief one participating... should be erased."

The regime's chief representative in Geneva Bashar al-Jaafari also said on Friday the talks would continue after the weekend.

"We will meet with Mr. de Mistura for a fifth time on Monday at 11:00 am (0900 GMT)," he told reporters following a meeting with the UN envoy, speaking through a translator.

A source close to the government delegation told AFP on condition of anonymity that the delegation would "stay in Geneva until Wednesday at least."

De Mistura was meanwhile pushing ahead with his marathon of meetings.

He was set later Friday to meet the so-called internal opposition, which is based inside Syria and tolerated by the government and which is not opposed to Syrian President Bashar al-Assad remaining in power.

The UN envoy hinted to Swiss public radio late on Thursday that the HNC's departure was a bid to apply pressure to the process.

"There is a lot of what we call political gesticulation, and that is normal," he said.