By John Irish

LONDON (Reuters) - France is alarmed by the Syrian government's tightening siege of Aleppo and the risk it will carry out a bloodbath near Damascus, and will push this week for more pressure on Syria's ally Russia, Foreign Minister Jean-Marc Ayrault said on Tuesday.

"We are extremely concerned by the situation in Aleppo, but Daraya as well," Ayrault told Reuters, referring to a rebel-held Damascus suburb seen as the epicenter of the uprising against President Bashar al-Assad.

"Daraya is a symbol and we fear a real massacre."

Daraya is besieged by forces loyal to Assad, who until last month had refused to allow aid to starving residents since 2012.

International aid convoys reached the town in June, but fighting continues and about 6,000 people are still trapped there.

Outside Aleppo, Syria's army and allied militia fighters backed by Russian air power this week seized the only road into the rebel-held part of the northern city, tightening a siege that has trapped some 200,000 to 300,000 people.

"France will not close its eyes to the drama of Aleppo," Ayrault said before a meeting on Syria in London with his British, U.S., German, Italian and EU counterparts.

"What we cannot accept is to wait for election calendars," he said referring to the November presidential election in the United States. "We need to launch a call to help those besieged."

As well as Western-backed rebels, Assad is also fighting the hardline Islamic State, which controls about a third of the country, and the local al Qaeda affiliate, the Nusra Front. The rebels of Aleppo and Daraya are supported by the same western countries that are conducting air strikes against Islamic State.

Ayrault said more pressure needed to be put on Moscow so it would in turn lean on Assad, something that he wanted like-minded countries to discuss when the U.S.-led coalition against Islamic State meets in Washington later this week.

After last week's attack in Nice, Ayrault said Paris would reiterate its readiness to step efforts against Islamic State or Daesh, which should now focus on its sanctuary in Raqqa, Syria.

Islamic State claimed responsibility for the Nice attack, in which a Tunisian man killed 84 people by plowing through a Bastille Day crowd with a truck.

"Our priority also, and this will be the objective in Washington, is that effort against Daesh is much stronger", Ayrault said.

(Reporting by John Irish; Editing by Andrew Callus and Mark Trevelyan)