Britain and France are stepping up pressure for a UN Security Council vote condemning the Syrian government's suppression of months of unrest.
French Foreign Minister Alain Juppe said it was "inconceivable that the UN remains silent" in the face of worsening violence.
Britain plans to present a draft resolution later on Wednesday.
But unlike the case of Libya, the draft does not suggest military action against Damascus or sanctions.
In Syria, residents of the northern town of Jisr al-Shughour are said to be fleeing ahead of an expected military assault, after the government said 120 security forces personnel had been killed there.
In a separate development, Syria's ambassador to France has denied reports in the French media that she had resigned.
Appearing on French TV, Lamia Chakkour said a telephone interview in which she was reported to have quit was part of a campaign of misinformation against the government of Syrian President Bashar al-Assad.
Revised draft
On Tuesday, a British spokesman at the UN said the draft resolution to the 15-member Security Council was expected to be presented on Wednesday afternoon.
The spokesman added that a vote was likely to take place later this week or early next week.
Earlier, Alain Juppe said that the repression in Syria was "getting worse" and that "the massacres are on the rise".
"It is inconceivable that the United Nations remains silent on such a matter. We are working with our UK friends to have as large a majority as possible on the Security Council," the French minister added after a council meeting.
However, some council members - like Brazil, South Africa and India - are afraid that the resolution could be the first step towards a Libya-style intervention, the BBC's Barbara Plett at the UN reports.
So Britain and France have revised the text to take in their concerns, diplomats say.
The idea is to build enough support in the council to make it politically difficult for Russian and China - two heavyweights who oppose any action on Syria - to veto the resolution, our correspondent says.
However, a senior Russian diplomat reiterated Moscow's opposition to the proposed resolution.
Speaking in Brussels, Russia's envoy to the EU, Vladimir Chizhov, said: "The prospect of a UN Security Council resolution that's along the same lines as Resolution 1973 on Libya will not be supported by my country. The use of force, as Libya shows, does not provide answers."
'Road barriers'
Meanwhile, residents of Jisr al-Shughour are said to be setting up checkpoints ahead of a possible assault by the military, after the government warned it would act "with force" to combat "armed gangs" that it blames for the recent killings.
The reported attack on security forces came amid mounting tensions as dozens of protesters were killed across the country over the weekend.
The BBC's Jim Muir in neighbouring Lebanon says there are no reports of action in Jisr al-Shughour itself yet, but that troop movements and preparations have been reported.
Some activists are said to have erected barriers of rocks, tree trunks and burning tyres on the main approach road to try to block the advance of security forces.
Our correspondent says Syrian television has been paving the way for the expected counter-attack, saying there was a popular consensus that the army should go in, and bolstering that with interviews of people praising the government.
One Jisr al-Shughour resident told AP news agency that many were fleeing the area for the Turkish border about 12 miles (20 km) away.
"People were struck by fear and panic after the government statements last night, it's clear they are preparing for a major massacre," he said.
A total of 122 Syrians crossed the border into Turkey overnight, Turkey's state-run Anatolian news agency said.
