Russia is pushing for a UN security council vote to support the ceasefire it helped broker in Syria, where the truce remained largely intact on its second day despite sporadic clashes.
Rebel supporter Turkey and key regime ally Russia, which brokered the truce, say the talks in the Kazakh capital, Astana, aim to supplement UN-backed peace efforts, rather than replace them.
Syrian rebel groups said they would consider a ceasefire deal brokered by Russia and Turkey “Null and void” if the Damascus government’s forces and their allies continued to violate it.
Russia, which supports the Syrian president, Bashar al-Assad, has urged the UN to give its blessing to the fragile ceasefire, the third truce this year seeking to end nearly six years of war in Syria.
Clashes and air strikes have persisted in some areas since the ceasefire began on Friday, though the Syrian Observatory for Human Rights, a monitoring group, said on Saturday the truce was still largely holding.
In their statement, the rebels said it appeared the government and the opposition had signed two different versions of the ceasefire deal, one of which was missing “a number of key and essential points that are non-negotiable,” but did not say what those were.
There has been confusion over which groups in the opposition are included in the ceasefire.