Russia, Turkey and Iran failed hammer out details over de-escalation zones, including setting the boundaries and policing the four safe zones in war-torn Syria, Moscow's chief negotiator said.
Russian delegation head Alexander Lavrentiev said that after the end of the latest two-day negotiations in Kazakhstan's capital Astana that documents outlining how the four zones should work "need finalising" despite being "essentially agreed" between the three key power-brokers.
Moscow and Tehran, which back Syrian regime leader Bashar al Assad, and rebel supporter Ankara agreed in May to establish four "de-escalation" zones in a potential breakthrough after years of fighting that has claimed more than 320,000 lives and displaced over 10 million people.
TRT World's Iolo ap Dafydd reports details of talks.
While fighting dropped off in the weeks after the deal, it has ratcheted up in some areas since, and the international players have yet to finalise the boundaries of the zones or determine who will police them.
"We have not yet managed directly to establish the de-escalation zones," Lavrentiev said, insisting however that "de-facto" safe areas already existed on the ground.
He added that there had been no definitive agreement over the contentious issue of "which specific forces" would police the zones.
Regime leader blames Ankara
A working meeting of representatives from Russia, Iran and Ankara is set to take place in Tehran at the start of August to help thrash out the remaining disagreements, Russian news agencies cited a joint statement as saying.
Syrian regime's lead negotiator Bashar al Ja'afari, however, blamed Turkey for blocking the agreement saying because of Ankara's position the talks have achieved "very modest" results.
Earlier Russia said that it may deploy its military to police the borders of planned de-escalation zones in Syria within two to three weeks after finalising an agreement with Turkey and Iran - which didn't materialise on Wednesday.
Moscow's negotiator Alexander Lavrentiev insisted that the borders of two zones - in rebel-held parts of Homs and around Eastern Ghouta close to Damascus - were "essentially" agreed.
But there were "still questions" about the safe zone meant to cover the Idlib province on the Turkish border and "some reservations" about another one across swathes of southern Syria, he said.