UNITED NATIONS: Britain, France and the United States asked the UN Security Council to hold a vote later Thursday on a resolution demanding an investigation of the suspected chemical attack in Syria, diplomats said.

It remained unclear whether Russia would support the measure, which was slightly revised following negotiations over the past two days.

Britain, France and the United States circulated the draft resolution following the strike Tuesday on a rebel-held town in Idlib province that left 86 people dead, including 27 children.

Results from post-mortems performed on victims from the town of Khan Sheikhun point to possible exposure to sarin, according to Turkish health officials.

Russia has rejected the proposed resolution as "categorically unacceptable" and proposed a rival draft that did not include demands for the Syrian government to cooperate with an investigation.

France earlier warned Russia against resorting to its veto power to block the measure from adoption at the Security Council.

"That would be a terrible responsibility in front of history," French Ambassador Francois Delattre told reporters.

Asked whether he expected Russia to resort to a veto, Delattre said: "I would not say that. I think there is still a chance. I hope so."

Diplomats said the council could hold the vote around 7:00 pm (2300 GMT).

Russia has used its veto power seven times to block UN action that would put pressure on its ally Syria.

The draft resolution backs an investigation by the Organisation for the Prohibition of Chemical Weapons and demands the Syrian government provide information about its military operations on the day of the strike.

The text calls on Syria to provide flight plans, flight logs and other information on its military operations on April 4 and to hand over the names of commanders of helicopter squadrons.

Britain, France and the United States blame President Bashar al-Assad's forces for the attack, but the Syrian army has denied any involvement.

Russian President Vladimir Putin said it was unacceptable to make "unfounded accusations" over the "incident with chemical weapons" in Syria, the Kremlin said.-AFP