Syrian rebel groups said on Monday they had decided to freeze any talks about their possible participation in Syrian peace negotiations being prepared by Moscow in Kazakhstan unless the Syrian government and its Iran-backed allies end what it said were violations of a ceasefire.

In a statement, the rebel groups also said that any territorial advances by the army and Iran-backed militias that are fighting alongside it would end the fragile ceasefire brokered by Russia and Turkey, which back opposing sides, that came into effect on Friday.

"The regime and its allies have continued firing and committed many and large violations," said the statement signed by the mainly moderate rebel groups operating under the umbrella of the Free Syrian Army (FSA).

Vladimir Putin announces ceasefire agreement in Syria

The UN Security Council on Saturday gave its blessing to the ceasefire deal, which are slated to be followed by peace talks in the Kazakh capital, Astana.

The statement said the main violations were in an area northwest of Damascus in the rebel-held Wadi Barada valley, where government forces and the Iran-backed Lebanese Hezbollah group have been trying to press advances in an ongoing campaign.

Aleppo before the Syrian Civil War Show all 12 1 /12 Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War A man crosses a street in Aleppo, December 12, 2009 Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War A vendor sits inside an antique shop in al-Jdeideh neighbourhood, in the Old City of Aleppo, December 12, 2009 Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War A view shows part of Aleppo's historic citadel, overlooking Aleppo city, Syria Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War A view shows part of Aleppo's historic citadel, Syria Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War Visitors walk inside Aleppo's Umayyad mosque, Syria Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War People walk inside the Khan al-Shounah market, in the Old City of Aleppo, Syria Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War A man walks past shops in al-Jdeideh neighbourhood, in the Old City of Aleppo, Syria Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War People walk along an alley in al-Jdeideh neighbourhood, in the Old City of Aleppo, Syria Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War Visitors tour Aleppo's historic citadel, Syria December 11, 2009 Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War A general view shows the Old City of Aleppo as seen from Aleppo's historic citadel, Syria December 11, 2009 Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War People walk near Aleppo's Bab al-Faraj Clock Tower, Syria October 6, 2010 Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War A man stands inside Aleppo's historic citadel, overlooking Aleppo city, Syria December 11, 2009 Reuters

Rebels say the army is seeking to recapture the area, where a major spring provides most of Damascus's water supplies and which lies on a major supply route from Lebanon to the Syrian capital used by Hezbollah.

Like previous Syria ceasefire deals, it has been shaky from the start, with repeated outbreaks of violence in some areas, but has largely held elsewhere.

The rebel groups questioned Russia's ability to force the Syrian government and their allies to abide by the terms of the ceasefire deal.