Russia on Monday rejected Arab and Western calls for a deadline to be set for the Syrian regime's implementation of a peace plan put forward by international mediator Kofi Annan.
"Ultimatums and artificial deadlines rarely help matters," Foreign Minister Sergei Lavrov said while on a visit to the former Soviet nation of Armenia.
Lavrov added that only the UN Security Council on which Russia wields veto power could put any time restrictions on Syrian President Bashar al-Assad's compliance with the six-point initiative.
"Annan has a Security Council mandate and it is up to the UN Security Council to decide who is complying with this plan and how," he said.
The so-called "Friends of Syria" meeting of Arab and Western nations in Istanbul agreed this weekend to ask the United Nations to give Assad a deadline to cooperate with Annan's solution to the year-long conflict.
The plan itself demands that Assad pull out his forces from major flashpoint cities and introduce a daily two-hour ceasefire that could let aid workers deliver supplies and treat the thousands of injured civilians.
But it puts forward no time frame in which Assad has to comply.
Lavrov said the peace plan would not work unless rebel forces also agreed to halt fire.
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"The demands should be put to all sides of the barricades," Lavrov said.
"We intend to be friends with both sides in Syria," he added in reference to Russia's past support for Assad.
The Russian foreign ministry had earlier issued a statement saying the "Friends of Syria" meet contradicted the objective of reaching a peaceful settlement by openly siding with the opposition.
"The promises and intentions to deliver direct military and logistical support to the armed... opposition that were voiced in Istanbul unquestionably contradict the goals of a peaceful settlement to the civil conflict in Syria," the foreign ministry statement said.
Russia has been under mounting international pressure to break its Soviet-era ties with the Damascus leadership and call on Assad to step down.
Moscow has in recent weeks stepped up criticism of the Syrian strongman and accused the Damascus government of failing to follow Russia's advice on ways out of the conflict.
Yet it has also accused the West of breaking international law by issuing unilateral calls for Assad's ouster.
Lavrov said Monday that the opposition Syrian National Council (SNC) that the Istanbul meeting recognised as the "legitimate representative" of all Syrians reflected the views of only a fraction of the country's people.
"When decisions are made to call one group the legitimate representatives of the Syrian people, one might jump to the conclusion that the other Syrians -- both organisations and the authorities -- are not legitimate," Lavrov said.
"I think this approach is dangerous and works against the efforts being put forward by Kofi Annan."