DAVID Cameron has been forced to defend British military interventions amid scepticism over the "growing drumbeat" towards air strikes in Syria.

The Prime Minister insisted the air strikes he ordered in Libya in 2011 on balance had benefited the UK because they had helped oust the dictator Muammar Gaddafi from power.

But SNP Westminster leader Angus Robertson highlighted the "total anarchy" and "civil chaos" in the North African nation, which was split between an Islamist-backed government based in Tripoli and an internationally-recognised administration in the east.

Mr Robertson suggested the PM had not learnt the lessons of the Libya intervention as well as Labour-instigated wars in Iraq and Afghanistan and cautioned him about extending British air strikes against Isis militants to Syria.

Mr Cameron is widely expected to call a Commons vote to authorise action against Isis, also known as Daesh or Isil in the war-ravaged nation; a Cabinet source has indicated he is increasingly confident that at least 50 Labour MPs could back extending RAF strikes from Iraq to Syria.

During Prime Minister's Questions, Mr Robertson noted how more than 450 UK service personnel had died in Afghanistan but sadly the Taliban were back and that the UK had spent 13 times more bombing Libya than in rebuilding the country, which was racked by anarchy.

"The US has just dropped a $500 million programme to support the Syrian opposition, Russia is bombing Syria and the UK has no plan to help Syrian refugees who have made it to Europe. There is no surprise that there is growing scepticism about the drumbeat towards war.

"Will the Prime Minister give an assurance that he has learned the lessons of Iraq, of Afghanistan, and Libya and he will never repeat them?"

Mr Cameron responded by saying he could not remember a question with so many errors in it.

Noting how Britain was the second largest bilateral donor to Syrian refugee camps in Jordan, in Lebanon, in Turkey, the PM told Mr Robertson: "We've done more than almost any other country in the world to help Syrian refugees but frankly, I don't recognise the picture you paint of Afghanistan; the fact is that we have supported an Afghan national army and police force and an Afghan government that are in control of that country.

"But the final point I'd make to you is it's all very well standing on your high horse and lecturing about the past; would you be happier with an Afghanistan that had a Taliban regime and al Qaida in Afghanistan? Would you be happier with Gaddafi running Libya, would you be happier with that situation?”

He added: “So as I said, the consequences of non-intervention are also worth considering."

Meantime, Labour has indicated it could support the extension of RAF air strikes against Isis to cover Syria as well as Iraq without the backing of a United Nations Security Council resolution.

Last month, the party conference voted not to support military action in Syria without the authorisation of the UN.

But Hilary Benn, the Shadow Foreign Secretary, signalled that Labour would "look at the position again" if a security council resolution were vetoed by Russia. He noted how inaction would have "consequences" on the ground for people in Syria.