BEIRUT/AMMAN (Reuters) - Syrian rebels cast doubt on Monday that they would attend Russian-backed peace talks this week, accusing Moscow of failing to get Damascus to fully comply with a ceasefire or take any confidence-building steps.

Kazakhstan said on Saturday it had invited the government and rebels for Feb. 15-16 talks. They attended a similar indirect meeting in the Kazakh capital Astana last month aimed at shoring up a ceasefire brokered by Turkey and Russia, President Bashar al-Assad’s most powerful ally.

“The opposition factions will not attend Astana because the Russian side did not abide by what they agreed to before during and after Astana to uphold the ceasefire agreement,” Mohammad Al Aboud, a senior rebel official, told Reuters.

A second rebel official, speaking on condition of anonymity, said at most a handful of rebels might attend, but only if progress was seen in the next two days.

Russia had so far failed to yield any tangible steps towards full implementation of the ceasefire, humanitarian aid access, or a release of female detainees the rebels had demanded at the first Astana meeting, he added. “It seems Russian pressure is of no benefit,” the official said.

Russia and Turkey, which backs the rebels, have sought to revive diplomacy towards ending the war since the Syrian government and its backers defeated the rebels in Aleppo in December, their biggest defeat of the conflict.

A new round of U.N.-backed peace talks are due to begin in Geneva next week.

The Syrian government said earlier on Monday it was ready to agree on prisoner swaps with rebel groups, which the opposition wants before any negotiations over Syria’s political future.

Syrian state media cited an official source as saying the government was “always ready” to exchange prisoners in its jails for people “kidnapped by terrorist groups”.

A rebel official dismissed the statement as a ruse, saying Damascus had far more detainees than the few the rebels held.

NEXT ROUND OF TALKS

Rebels accuse Russia of failing to pressure the Syrian army and its Iranian backed militias to end what they see as violations of the Turkish-Russian ceasefire.

Separately, rebel fighters and the army engaged in heavy clashes in the southern city of Deraa, near the Jordanian border, with jets striking rebel outposts in the old quarter.

Rebels drawn from both moderate Free Syrian Army (FSA) and jihadist groups launched the assault on Sunday on the strategic district of Manshiya in a bid to seize it.

The district’s capture would thwart an army goal of trying to secure a border crossing with Jordan that would allow the army to open a direct commercial route all the way to Damascus.

The United Nations special envoy for Syria, Staffan de Mistura, sent invitations on Monday for the Geneva talks beginning on Feb. 23, after initial prior consultations beginning on or about Feb. 20, his spokeswoman Yara Sharif said.

The main Syrian opposition body on Sunday approved its delegation to next week’s Geneva talks.

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

Amnesty International said in a report this month that the government had executed up to 13,000 prisoners in mass hangings at a military jail near Damascus. The Syrian justice ministry called the report “devoid of truth”.