Prime Minister David Cameron has appealed to the House of Commons to support military action against Syria over the use of chemical weapons.

He said it was "beyond doubt" President Assad's regime was behind the attack on 21 August, and told MPs there was a "clear legal basis" for military action.

Labour leader Ed Miliband said he did not rule out military action, but asserted that "we need to be clear-eyed" about the impact of intervention.

MPs were brought back early from their summer recess on 29 August 2013 to debate and vote on whether the UK should get involved in military strikes on Syria.

Setting out the government's case to a packed chamber, Mr Cameron insisted military intervention was not about taking sides in the conflict, regime change or invasion, but a response to a "war crime".

"Put simply, is it in Britain's national interest to maintain an international taboo about the use of chemical weapons on the battlefield? My argument is yes it is."

He admitted there was "no smoking piece of intelligence" to prove the Assad regime carried out the attack, but insisted he was convinced by the evidence.

The government was forced to water down its initial motion after Labour hardened its position and signalled it would not support it.

Mr Miliband said the prime minister needed to set out a "better case for action", arguing that Britain's response should not be based on a "political timetable set elsewhere".

His party's amendment sets out a "road map" for action, he explained, including gathering "compelling evidence" that the Assad regime was to blame for the attack.

The amendment, co-signed by Plaid Cymru and the SNP, also calls for a greater role for the United Nations before any military action is authorised.

UN chemical weapons inspectors are investigating one of the sites affected by a suspected attack, and are export to report back to the UN on Friday.

The Syrian government has strongly denied that it used chemical weapons and blames opposition fighters for the attack.

Watch part two of the debate here.