* U.S., France, Britain to press Assad over chemical arms
* Allies seek strong U.N. resolution
* Idea is to take "firm line", says France
The United States, France and Britain agreed on Monday to step up pressure on President Bashar al-Assad to stick to the terms of a deal under which Syria is to give up its huge arsenal of chemical weapons and avoid U.S. military strikes.
The three Western permanent members on the United Nations Security Council agree to seek a strong resolution in that forum that sets binding deadlines for the removal of Syria's chemical weapons, French President Francois Hollande's office said.
The statement followed talks in Paris, two days after the United States reached a deal with Assad's ally Russia on chemical weapons that could avert U.S. strikes on Syria.
U.S. Secretary of State John Kerry told a news conference in Paris that the three powers agreed with Moscow that Assad must suffer consequences if he fails to comply with U.N. demands. The accord offered the Syrian leader "no lifeline" and he had "lost all legitimacy", Kerry added.
After Hollande met Kerry and British Foreign Secretary William Hague and their French counterpart Laurent Fabius, an aide to Hollande said: "The idea is to stick to a firm line."
"They've agreed to seek a strong and robust resolution that sets precise and binding deadlines with a calendar," said the official, who spoke on condition of anonymity.
Syria's government at the weekend hailed as a "victory" the Russian-brokered deal, which rebels who have been fighting to overthrow the government in Damascus since 2011 says has benefited their enemy in the civil war.
Assad briefly dispersed his forces to protect them from strikes threatened by the United States as punishment for a chemical weapons attack in Damascus on Aug. 21 which Washington says killed more than 1,400 people, many of them children.
Government jets and artillery hit rebel suburbs of the capital again on Sunday in an offensive that residents said began last week when President Barack Obama delayed air strikes in the face of opposition from Moscow and in the U.S. Congress.
The deal reached in Geneva has put off the immediate threat of air strikes but Obama has stressed that force remains an option if Assad reneges. U.S. forces remain in position.
Russia still opposes military action but now backs possible U.N. sanctions for non-compliance.
Kerry has responded to widespread doubts about the feasibility of what he called "the most far-reaching chemical weapons removal ever" by insisting the plan could work.
The Syrian government has told the United Nations it will adhere to a treaty banning chemical weapons. The U.S.-Russian framework agreement calls for the United Nations to enforce the removal of existing stockpiles by the middle of next year.
Assad has less than a week to begin complying with the deal by handing over a full account of his chemical arsenal. He must allow U.N.-backed inspectors from the Hague-based Organisation for the Prohibition of Chemical Weapons (OPCW) to complete their initial on-site checks by November.
Assad told Russian state television last week that his cooperation was dependent on an end to threats of war and to U.S. support for rebel fighters. But it seems likely that Moscow can prevail on him to comply, at least initially, with a deal in which Putin has invested considerable personal prestige.
While Russian Foreign Minister Sergei Lavrov stressed in Geneva that the pact did not include any automatic use of force in the event of Syria's failure to comply, Western leaders said only the credible prospect of being bombed had persuaded Assad to agree to give up weaponry which he had long denied ever having, let alone using.
Experts say the removal of up to 1,000 tonnes of chemical agents will be highly problematic in the middle of Syria's civil war, although they assume that the dozens of chemical weapons sites remain under government control.