London: Britain`s National Security Council (NSC) on Wednesday said the use of chemical weapons by President Bashar al-Assad`s regime was "unacceptable", strengthening the government`s hand for possible military intervention in Syria.
The NSC, which includes Defence Secretary Philip Hammond, Home Secretary Theresa May, Deputy Prime Minister Nick Clegg, and military and intelligence chiefs, further said "the world cannot stand by".
Prime Minister David Cameron tweeted the decision after an emergency meeting of the NSC that lasted over an hour. The body meets weekly to discuss national security matters.
The government earlier decided to put forward a resolution to the UN Security Council for "authorising necessary measures to protect civilians" in Syria.
The resolution will be presented at a meeting of the five permanent members of the Council, Cameron said in an earlier tweet.
Russia and China vetoed earlier resolutions critical of Syria and may block any text deemed to approve military action.
A statement from 10 Downing Street said Britain would seek a measure "authorising necessary measures to protect civilians" in Syria under Chapter 7 of the UN Charter.
Military force is one of the options that can be authorised under that section.
Earlier, Cameron spoke to US President Barack Obama on phone as the two countries considered military intervention in Syria.
The Syrian government has blamed opposition fighters for an alleged chemical attack near Damascus on August 21, in which hundreds of people were reportedly killed.
The phone call between Obama and Cameron was the second since the alleged attack.
Downing Street said Cameron heard the "latest on US thinking" on the issue, ahead of a House of Commons vote scheduled for Thursday.
"No decision has yet been taken. Any action we take or others take would have to be legal, would have to be proportionate," Cameron said.
"It would have to be specifically to deter and degrade the future use of chemical weapons," he said in an interview.
Cameron said the question the world community needs "to ask is whether acting or not acting will make the use of chemical weapons more prevalent."
The UK government is expected to publish the House of Commons motion for debate today, along with details of intelligence linking the Syrian government to the attack.
The US has said its forces are "ready to go" but former UK military chiefs warned a one-off missile strike could see the UK dragged into deeper action.