Cameron spells out plans to blitz Isil for several years
British Prime Minister David Cameron has set out his detailed case for British airstrikes against Isil in Syria as part of a "comprehensive" strategy to tackle the group.
Mr Cameron warned that the war could take several years.
He broke his approach down into seven points, aiming to address concerns raised by the Foreign Affairs Committee in a report earlier this month.
They included building international support to end the civil war and begin a "transition" from Bashar Assad's regime, as well as boosting Syrian groups fighting Isil and cutting off the terrorists' funding streams.
But Mr Cameron rejected the idea that the UK should wait for these efforts to come to fruition before attacking strongholds such as Raqqa, saying the UK could add to the coalition's military capabilities.
Mr Cameron also reassured MPs that he only wanted the RAF to attack Isil targets - in contrast to two years ago, when the Government lost a vote that would have authorised strikes on Assad's forces.
Labour leader Jeremy Corbyn raised the prospect that British intervention could increase civilian deaths in the Syrian conflict.
He asked seven questions about the impact of bombing Syria in his response to the Prime Minister in the House of Commons.
They included whether the strategy could actually defeat Isil, whether British troops would be deployed on the ground and how water-tight the UN Security Council resolution was.
Mr Corbyn also questioned whether bombing would improve the chance of a political statement, increase terrorist attacks on Britain, or increase civilian deaths.
There was a measured and respectful debate lasting more than two and a half hours yesterday, with 103 MPs asking questions of Mr Cameron.
The Scottish National Party's leader at Westminster, Angus Robertson, indicated that his party was likely to oppose the military action.
Mr Corbyn warned of "unintended consequences" from airstrikes, but stopped short of saying he would oppose them.
A number of Tories who had previously voiced reservations about extending action seemed to have been won over - including, crucially, the Foreign Affairs Committee chairman Crispin Blunt.
However, other speakers doubted Mr Cameron's claim that there are 70,000 Syrian fighters on the ground and ready to battle Isil. Mr Cameron made clear he was not setting a timetable for a vote - or even committing to hold one.
He said he would not bring the issue to the House if there was a chance of losing, for fear of handing Isil a propaganda victory.
However, the position of the Labour leadership - and whether they grant their MPs a free vote - could be crucial.
The shadow Cabinet held a 90-minute meeting after Mr Cameron's statement to discuss its approach, without coming to any firm conclusion.
Members have now been sent away to consult with their constituency parties and consider over the weekend, before meeting again on Monday ahead of a potentially explosive parliamentary party session in the evening.
It appears very unlikely that Mr Corbyn will be able to unite his team on a single position. He and shadow chancellor John McDonnell have already indicated they oppose Western military involvement in the Middle East, while a number of other senior figures are thought to be in favour of targeting Isil in Syria.
That would leave Mr Corbyn with a choice between ordering his MPs to vote against - raising the possibility of a hugely damaging rebellion - or allowing a free vote and admitting his team cannot agree on a key matter of national security.
Shadow foreign secretary Hilary Benn said there were "compelling arguments" for extending RAF air strikes from Iraq into Syria.
"We are trying to make life difficult for Isil/Daesh in Syria and I think there's a very strong case for us playing our full part in doing that, given that we are currently flying missions, providing intelligence and refuelling to others who are participating," Mr Benn said.
"I think our allies look to us - particularly the French, after the grievous blow they have suffered in Paris - and they want to feel we are with them in solidarity, and I think we should be."
But Labour's Diane Abbott said she had questions about air strikes in Syria.
"I'm not sure that it would make British people safer at all. The worry is about ground troops. I do not believe there's any support in the country for British troops getting involved in a ground war in Syria."
A senior Labour source said the meeting had been "businesslike" and most shadow cabinet members spoke.
The source said "clarification" was needed on the exact form of the motion and talks with the Government were likely to take place over the weekend.
"If you are asking the shadow cabinet to make a decision they need to know what they are making a decision on," the source said.
They added that "most people" doubted there were 70,000 Free Syrian Army forces on the ground.
The meeting has "adjourned" until Monday, when another discussion will be held before a potentially crunch parliamentary party session.
However, the source said there was no deadline for a decision as no vote had been called.