Media playback is unsupported on your device Media caption Alex Salmond on Syria air strikes

The SNP's foreign affairs spokesman Alex Salmond has said a UN mandate would be a condition for his party to support military action in Syria.

The former nationalist leader spoke after his successor Nicola Sturgeon told the BBC she was "prepared to listen" to the case for air strikes.

The position of SNP MPs could be crucial if a Commons vote is held on a fresh campaign.

The issue came to the fore following the Paris attacks which killed 129.

Downing Street said there was still no timetable for a vote on extending UK military action but it was thought it could happen before Christmas.

The SNP unanimously opposed UK military action in Syria at its conference in Aberdeen last month.

Mr Salmond said the UK government had not yet made a convincing case for joining military action against so-called Islamic State.

Media playback is unsupported on your device Media caption Nicola Sturgeon spoke to BBC Scotland's Glenn Campbell

In a BBC interview he said: "We haven't heard in the SNP benches anything yet that would convince us that being the thirteenth country to start bombing in Syria is going to make any material difference whatsoever to anything.

"What we'd like to hear is far, far more about diplomatic initiatives through the United Nations and also the real practical things like interrupting the financial flows into Daesh to actually make a material difference to what's happening in the Middle East."

Mr Salmond said the role of the United Nations was important because it was regarded as the "voice of the international community".

He added that the involvement of the UN "would be a condition of the SNP looking at this issue [air strikes in Syria]".

When asked by Andrew Neil of the BBC's Daily Politics if his main condition of air strikes was a UN resolution, the MP said "yes it was".

Mr Salmond added: "The reason for a UN resolution being a precondition, not just of this conflict but of the SNP's approach to many conflicts, is without that resolution you can't bring about peace."

'Not yet convinced'

However, Ms Sturgeon, who is marking her first anniversary as first minister, told BBC Scotland she was willing to consider what David Cameron had to say.

She explained: "I'm not yet convinced the case for air strikes has been made. That is not to say I will not listen to the case that David Cameron will make.

"But Syria, and I know David Cameron understands this, is a horrendously complex situation and it is not a case of Isil against everybody else.

"We have a complicated, multi-layer civil war going on in Syria as well as the threat that is posed by Isil so I think there are some tests that require to be passed in order for the case for air strikes to be made."

Ms Sturgeon said these tests included the legality of any military action, as well as the question of where air strikes fitted into a "wider and bigger strategy" for combating the Islamic State group.

The MSP told the BBC's Glenn Campbell: "If there is not to be a security council resolution - and he made comments in the House of Commons about what he saw as being the difficulty with that - then he has to outline what he considers to be the legal basis."

She added: "I think it is incumbent on the prime minister if he is going to bring forward a proposal for air strikes to the House of Commons that he makes that case and that he addresses these key points that are not just being raised by the SNP but by the foreign affairs committee in the House of Commons itself."

And, like Mr Salmond, she questioned whether air strikes in Syria, being carried out by countries including France and the US, were making the situation better or worse.

International community

Speaking in the Commons on Wednesday, Mr Cameron made it clear that he believed the UK could take military action in Syria without the explicit authority of the United Nations Security Council.

The prime minister stressed that while a UN Security Council resolution would be welcome, he believed it was not necessary and he would not "outsource to Russian veto" decisions about Britain's safety.

The UK government is said to be increasingly confident it can convince enough MPs in the Commons to back military action in Syria.

Labour leader Jeremy Corbyn said on Tuesday that any military response should have the support of the international community and legality from the United Nations, but he has faced criticism from many of his own MPs for his refusal to back further UK involvement.