Britain's Prime Minister David Cameron said the United Nations Security Council's resolution to redouble action against ISIS in Syria was an "important moment", strengthening his bid to start air strikes against the militant group there.
The United Nations Security Council unanimously adopted a resolution on Friday drafted by France in the wake of a series of attacks in Paris a week ago that killed 130 people and were claimed by Islamic State.
"This is an important moment," said Cameron in a statement soon afterwards.
"The international community has come together and has resolved to defeat this evil, which threatens people of every country and every religion."
Britain is already involved in air strikes against ISIS militants in Iraq.
Cameron wants to extend the operation to hit ISIS in Syria to fall into line with allies, and has said he will submit a plan to parliament to do so.
Islamic State has seized large areas of territory in Syria and neighbouring Iraq. A U.S.-led coalition has been bombing the militants for more than a year and Russia started air strikes in Syria in September.