Russia shot down suggestions from some United Nations Security Council members on a draft resolution of an imminent deal aimed at stopping Syria's upheaval, warning it would veto the current text if it were put to a vote on Friday.

Pakistan's UN envoy said on Thursday that the council was "two words away" from an agreement, and the council chairman from Togo said a consensus was near on an amended version of a draft backing an Arab League plan for Syrian President Bashar al-Assad to step down.

But Russian Ambassador Vitaly Churkin told a closed-door session of the world body that Moscow would veto the draft if it were submitted on Friday with a phrase saying the council "fully supports" the plan, several Western diplomats told Reuters.

European and Arab drafters of the text planned to revise the text in a last-ditch attempt to allay Russian concerns and submit an amended version of the resolution to the council, diplomats said.

Morocco's UN envoy Mohammed Loulichki told reporters after Thursday's council meeting that he would deliver the new draft to the council and seek a vote "as soon as possible".

US Ambassador Susan Rice made clear that the council had once again failed to reach an agreement. "We had what I would characterize as sometimes difficult but ultimately useful discussions," she said. "We're still working. This is not done."

Churkin told reporters that Thursday's inconclusive negotiations were "something of a roller-coaster".

"We have a text which we are going to report to our capitals," he said. He declined to provide details but suggested how Russia might vote remained an open question. He said the fact that the draft could reach the council "does not pre-judge anything in any way".

Colombian Ambassador Nestor Osorio said council members would continue their discussions on Friday.

Submitting what some diplomats say is a final draft resolution does not necessarily mean a vote is imminent and further revisions could follow. France said it expects a vote on Friday, Saturday or Monday at the latest.

Russia has balked at any language that would open to door to "regime change" in Syria.

On Friday, three children were killed when an explosive device planted by unidentified gunmen went off in Syria's northern province of Idlib, according to private al- Ekhbariah TV.

An eyewitness in the area confirmed the blast, saying that he heard a loud explosion in the area.

The Sham FM radio put the death toll of the blast at four civilians, without giving further details. A day earlier, an unidentified group fired a mortar shell which landed near a hospital in Idlib, but no injuries were reported, according to Sham FM.