The Cabinet will meet tomorrow to approve a UK response to the Syrian chemical weapons attack agreed unanimously by the National Security Council, Downing Street said.
Prime Minister David Cameron gathered the UK's armed forces and security chiefs with key cabinet ministers in Downing Street earlier for emergency talks over possible military action.
Chief of the Defence Staff General Sir Nick Houghton and MI6 chief Sir John Sawers, Defence Secretary Philip Hammond and Attorney General Dominic Grieve were among those around the Cabinet table at 10 Downing Street to discuss the options.
"The National Security Council met this afternoon to consider the Government's response to the appalling chemical weapons attack near Damascus last week," a Number 10 spokeswoman said.
"The NSC agreed unanimously on a recommendation that the Cabinet will consider tomorrow.
"Ministers agreed that the (Bashar) Assad regime was responsible for this attack and that the world shouldn't stand idly by and that any response should be legal, proportionate and specifically to protect civilians by deterring further chemical weapons use."
The NSC also backed the UK's move to table a draft resolution to be debated by the five permanent members of the UN Security Council later in an effort to show willing to secure international support.
The resolution would authorise "all necessary measures to protect civilians" and condemns "the chemical weapons attack by Assad".
"The NSC agreed unanimously that the use of chemical weapons by Assad was unacceptable - and the world should not stand by," the Prime Minister wrote on Twitter.
The meeting is expected to help shape the wording of a motion to be voted on tomorrow by MPs, who have been recalled from their summer break to debate the Syria crisis.
Cameron insists any use of force would only be a response to the use of banned chemical weapons and would be legal and proportionate.
But there is widespread scepticism among MPs of all parties about the wisdom of a Western military intervention in the brutal civil war.
Labour has made a fresh effort to make UN backing for a military intervention one criterion for voting with the Government in tomorrow's vote.Suggest a correction