The Syrian government signalled on Monday that it was ready to agree to prisoner swaps with rebel groups, a confidence-building measure that might help both sides prepare to attend peace talks.

The government is "continuously ready" for such an exchange with rebel groups, "particularly in the framework of efforts being made for the coming meeting in Astana", a news flash on the state-run Al Ikhbariya TV station said, citing an official source.

Al Jazeera's Andrew Simmons, reporting from the Turkish city of Gaziantep along the Syrian border, said it was "difficult to know how significant this is because there have been prisoner swaps in the past".

Russia, Turkey and Iran - who created a trilateral mechanism to enforce the fragile ceasefire in Syria last month in Astana - are set to meet again in the Kazakh capital later this week.

The Kazakh foreign ministry said over the weekend that the Syrian government and rebel delegations had been invited to attend the meetings, set for February 15-16.

The meetings in Astana were originally aimed at consolidating the truce in Syria, a nationwide halt in the fighting established late in December that has steadily fallen apart over the past month.

The Astana talks were also meant to pave the way towards peace negotiations Geneva, tentatively set to begin on February 20.

"Originally, the thought was this was going to be a final attempt to get the ceasefire really tightened up in advance of the Geneva talks, but now there are suggestions that it could be more than that ... that there is some sort of peace deal on the table that might have legs for Geneva ... [it's] not clear yet," said Simmons.

The Syrian government has conducted prisoner exchanges in the past with a wide range of rebel groups under the auspices of the Syrian Red Crescent and the International Committee of the Red Cross.

This month, in a rare move, the Syrian government and rebel groups swapped dozens of female prisoners and hostages, some of them with their children, in Hama province in northwestern Syria.

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Syria's main opposition body approved, on Sunday, a new delegation to take part in Geneva talks later this month, which includes Russian-backed blocs that have been critical of the armed insurrection against Syrian President Bashar al-Assad.

The High Negotiation Committee (HNC), the main umbrella group, said in a statement after two days of meetings in the Saudi capital, Riyadh, that the new 21-member negotiating team included members of two dissident alliances with which it has previously been at odds.

Those two alliances - the so-called Moscow and Cairo groups - have long disavowed the armed rebellion and insisted that political change can only come through peaceful activism. Their members include a former Syrian government minister with close ties to Moscow.

Mohammad Sabra, who was appointed as chief negotiator, told Saudi-owned Al Hadath news channel that the delegation brought together various groups. He also accused unidentified foreign powers of trying to impose their views on the composition of the delegation, an apparent reference to Russia.

The body also chose a new head of the negotiating team, Nasr al-Hariri, a veteran opposition figure from southern Syria.

The HNC said in the statement the goal of the negotiations was a political transition under UN auspices in which Assad had no role in the future of the country. But it steered away from its previous insistence the Syrian president should leave at the start of a transitional phase.

The HNC also said foreign powers had no right to present a vision of Syria's future political system without the consent of Syrians.

Russia last month tabled the draft of a proposed new constitution for Syria, though it insisted the document had been circulated for the purposes of discussion only.

The HNC represented the opposition in Geneva talks last year, but it was not invited to recently convened talks in the Kazakh capital, Astana.

The indirect talks between government and rebel delegates in Astana were held with the aim of shoring up a ceasefire brokered by Turkey and Russia.