By John Irish

PARIS (Reuters) - France accused Syria and its allies on Wednesday of using political uncertainty in the United States to launch "total war" against rebel-held areas in the country and said states opposed to President Bashar al-Assad would meet in Paris soon.

U.S. President-elect Donald Trump is only inaugurated on Jan. 20 and the outgoing administration is not expected to take an active role in Syria so close to leaving office. European diplomats have expressed concern that Assad may feel emboldened by Trump's vow to build closer ties with Russia, Syria's ally.

"Today one million people are besieged. Not just in Aleppo, but in Homs, Ghouta and Idlib, and that's the reality of the situation in Syria," Foreign Minister Jean-Marc Ayrault told reporters after a weekly cabinet session.

He did not say what the planned meeting might achieve to tackle five years of conflict which have killed hundreds of thousands of people and displaced half of Syria's population, but said protecting Syrian civilians was an urgent priority.

"France is taking the initiative to confront this strategy of total war by the regime and its allies, who are taking advantage of the current uncertainty in the United States."

A meeting of countries opposed to Assad, including the United States, Saudi Arabia and Turkey, will take place in the coming days in Paris, Ayrault said. A diplomat said the ministerial talks would happen in early December.

The U.N. Special Envoy for Syria also expressed concern on Tuesday that Assad could launch a new offensive to crush eastern Aleppo before Trump takes office. Intense bombardment of east Aleppo, including of hospitals, has left residents even more deprived of medicines, food and fuel in recent weeks.

Accusing Syria and its Russian and Iranian backers of "cynicism", German Foreign Minister Frank-Walter Steinmeier told parliament that the renewed strikes would merely add momentum to the cycle of violence.

"Far too many people right now believe they can profit from the power vacuum after the U.S. elections and play the military card," he said. "We have to break through this logic. The talks on ceasefires and humanitarian aid must not stop during this period of transition in Washington."

CHEMICAL WEAPONS

A Western diplomat in Geneva also expressed concern over Trump's pledge to fight Islamic State alongside Russia.

"Today with few exceptions we see Russia fighting the opposition, or rather civilians in besieged opposition areas, not Islamic State," he told Reuters. "If this is the fight Trump would want to join, it would destroy any prospects of a political solution."

"But if it means Washington would get Russia to start seriously fighting Islamic State, rather than the opposition, that is good."

France, a staunch backer of the anti-Assad opposition, is now actively pushing for a U.N. Security Council resolution to sanction Syria for the use of chemical weapons, Ayrault said.

An inquiry by the United Nations and the Organization for the Prohibition of Chemical Weapons (OPCW) has already found that government forces were responsible for three chlorine gas attacks and that Islamic State militants had used mustard gas.

"It's been proved that the regime and Islamic State have used chemical weapons so we now need sanctions and that's the resolution we want at the U.N. The international community must stop turning a blind eye," Ayrault said.

"We aren't going to sit and do nothing," he added.

Russia has said the inquiry's findings cannot be used to take action at the Security Council and that the Syrian government, which denies using chemical weapons, should investigate the accusations.

(Additional reporting by Jean-Baptiste Vey, Sabine Siebold in Berlinand Stephanie Nebehay in Geneva; Editing by Dominic Evans)