Britain is to seek UN Security Council backing for “all necessary measures to protect civilians” in Syria, Prime Minister David Cameron has announced.
A UK-drafted draft resolution will be put forward to a meeting of the five permanent members in New York this evening “condemning the chemical weapons attack by Assad”.
A Downing Street spokeswoman said: “Britain has drafted a resolution condemning the attack by the Assad regime, and authorising all necessary measures under Chapter 7 of the UN Charter to protect civilians from chemical weapons.
The Prime Minister has met with military chiefs today to discuss military action in Syria, in response to suspected chemical attacks last week that killed over 350 civilians.
Mr Cameron is chairing the National Security Council meeting at Downing Street to discuss possible military plans drawn up in response to the alleged chemical weapons attack.
United Nations Security Council, international envoy Lakhdar Brahimi said today that it seemed "some kind of substance" had been used near Damascus on 21 August killing hundreds of people, but that he awaited evidence from Western powers as well as UN inspectors currently visiting the sites.
Speaking during a news conference in Geneva, he added: “I think international law is clear on this. International law says that military action must be taken after a decision by the Security Council. That is what international law says.
“I must say that I do know that President Obama and the American administration are not known to be trigger-happy. What they will decide I don't know. But certainly international law is very clear - the Security Council has to be brought in.”
The Prime Minister spoke to US President Barack Obama last night ahead of the NSC meeting, a Downing Street spokesperson confirmed, where both leaders "agreed that all the information available confirmed a chemical weapons attack had taken place, noting that even the Iranian president and Syrian regime had conceded this." Mr Cameron and Mr Obama also "both agreed they were in no doubt that the Assad regime was responsible", the spokesperson added.
UK Foreign Minister William Hague, who is attending today's meeting, has called for the United Nations Security Council to "rise to its responsibilities by condemning these events [in Syria] and calling for a robust international response".
Writing for the Daily Telegraph, he said the use of chemical weapons in the 21st century "cannot go unchallenged", arguing that the UK "cannot permit our own security to be undermined by the creeping normalisation of of the use of weapons that the world has spent decades trying to control and eradicate".
He echoed comments made by Mr Cameron and his deputy Nick Clegg yesterday that an allied response must be "legal and proportionate".
Mr Hague continued: “This actual, repeated use of chemical weapons in Syria is a moral outrage, a serious violation of international humanitarian law and a challenge to our common security. We are now weighing with the United States and our other allies how to respond in a way that is legal and proportionate.
"The goal of any response should be to prevent further similar humanitarian distress, to deter the further use of chemical weapons in Syria and to uphold the global ban against their use.”
The Prime Minister had warned yesterday that the world cannot stand by after the attack in Syria and announced he was recalling Parliament to vote on how Britain would respond. However, he still faces strident opposition to intervention from a number of his own backbenchers and polling shows the public is deeply reluctant for the UK to become embroiled in military action. A YouGov pol showed 50 per cent of the public were against a missile strike.
The NSC meeting comes as United Nations weapons inspectors resumed their investigations at the site of the alleged chemical attack today, after the team's operation was suspended on Tuesday following concerns over security. The convoy transporting the team into the site was shot at by snipers on Monday when trying to enter the area. No-one was injured.
During a speech marking the centenary of the Peace Palace in The Hague, UN secretary general Ban Ki-moon urged the members of the Security Council to “find the unity to act”, describing Syria as the “biggest challenge of war and peace in the world today”.
"We must pursue all avenues to get the parties to the negotiating table,” he said.“The body entrusted with international peace and security cannot be missing in action. The Council must find the unity to act. It must use its authority for peace.
“The Syrian people deserve solutions, not silence. Our common humanity that all do their utmost to end this tragedy now.”
Australia, which takes over the chair of the Security Council on Sunday, are the most recent country to comment on Wednesday, adding to the Western view that the use of chemical weapons must be responded to.
"Everyone's preference would be for action, a response, under United Nations auspices," Foreign Minister Bob Carr said.
"But if that's not possible, the sheer horror of a government using chemical weapons against its people, using chemical weapons in any circumstances, mandates a response."
Former military chiefs have since issued stark cautions about the military direction Mr Cameron is considering taking, warning that even a “surgical” missile strike could end up dragging the UK into deeper action.
The Archbishop of Canterbury has also spoke and urged MPs not to rush their decision, warning of the “unforeseeable ramifications” of military action in Syria.