Syrian rebel groups said on Monday they had decided to freeze any talks about planned peace negotiations this month in the Kazakh capital Astana, unless the Syrian government and its Iran-backed allies ended what it said were violations of a four-day old 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 Russia-Turkey-brokered truce 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 a number of rebel groups.