Talks between key Syria war players in Kazakhstan's capital, Astana, have ended with Russia, Turkey and Iran agreeing on a mechanism to support a delicate ceasefire.

The meeting, organised by Russia and Turkey and attended by the government and the armed opposition, was aimed at strengthening a nationwide ceasefire that has largely held despite pockets of violence, and at paving the way towards United Nations-led political negotiations in Geneva on February 8.

It was not immediately clear whether the opposition or the government backed the communique.

READ MORE: Astana joint statement by Iran, Russia, Turkey: in full

The three nations also said they supported the willingness of the armed opposition groups to participate in the Geneva talks and that they were committed to "minimising violence, building confidence, ensuring humanitarian access, protection and free movement of civilians," according to a final statement read by Kairat Abdrakhmanov, the Kazakh foreign minister.

The mechanism will also seek to "prevent any provocations and determine all modalities of the ceasefire", the statement said.

"There are very intense discussions because this is not about a paper; it is about cessation of hostilities, which means saving lives," Staffan de Mistura, the UN envoy to Syria, said at the beginning of the second day of talks on Tuesday.

Opposition spokesman Yahya al-Aridi had earlier played down expectations that the rebels would sign a potential collective statement at the end of the talks, saying that several obstacles still needed to be overcome.

"I don't believe that the communique will be strong enough to be taken to the UN," said Aridi, citing a number of rebel demands, including the lifting of sieges, the release of prisoners and the delivery of aid to besieged areas, that he said had not yet been "confirmed".

READ MORE: Rebels focused on ceasefire at Astana peace talks

The talks mark the first time the Syrian opposition was represented solely by representatives of armed groups.

On Monday, delegates from the warring sides sparred over interpretations of the December 30 ceasefire brokered by Russia and Turkey, as their respective regional backers met behind closed doors to keep the meeting on track.

Bashar al-Jaafari, head of the Syrian government delegation, accused the opposition of "misinterpreting" the tenets of the truce, saying the "provocative tone and lack of seriousness in the opposition delegation chief's speech" had "irritated the attendees' diplomatic senses and experience".

Referring to the rebel delegation as "terrorists", Jaafari said opposition groups who signed the truce deal were "trying to undermine and sabotage the Astana meetings".