FORMER First Minister Alex Salmond has accused the UK Government of authorising bombing raids against IS in Syria "by stealth" after it emerged RAF pilots had taken part in air strikes despite MPs voting against the move.

David Cameron was last night facing calls to order a statement to Parliament after a human rights organisation uncovered revelations that British military personnel had been involved in attacks while embedded with allies.

A spokeswoman for the Prime Minister admitted he was aware of UK involvement with the action against IS in Syria, even though the Commons voted against the move in 2013 following a fraught debate.

Parliament has only authorised UK forces to attack IS targets in neighbouring Iraq, where they are operating at the invitation of the government in Baghdad.

Mr Salmond, the SNP's foreign affairs spokesman, said the action "clearly flouts" the democratic decision taken two years ago, when a Government motion was defeated by 13 votes.

He also said it was inexcusable that Michael Fallon, the defence secretary, had led a recent debate in the Commons about Syria yet made no mention that UK servicemen and women were already engaged in military action.

He added: "The Government's policy in this matter is entirely unacceptable - effectively overseeing a bombing campaign by stealth - and we need to know what the defence secretary knew, when he knew it, and when he was proposing to tell the country. He clearly didn't do so in the debate on 2 July.

"The case for bombing in Syria has simply not been made, and the complexity of the situation is such that support for one faction is unlikely to produce a desirable outcome.

"Experience tells us that interventions can have unforeseen consequences. Past interventions and extensions of military action could at best be described as counter-productive, and at worst have helped to replenish the dark well from which terrorism springs."

The SNP is tabling a series of urgent questions at Westminster over the revelations which emerged following a Freedom of Information request by the Reprieve human rights charity.

The spokeswoman for the Prime Minister said the policy of embedding UK personnel with allies was "well known" having existed since the 1950s.

She added that "upward of a dozen" Britons were embedded with other nations in the counter-IS campaign although currently none of them are pilots currently. They operated under the command of the organisations they were embedded with.

Tory backbencher John Baron said that ministers must come to the Commons to explain what had happened. "We had a major vote," he said. "There should be sensitivity on this issue, and we should be very sensitive to the fact that we have military personnel participating, in effect, in military intervention.

"Those individuals should be withdrawn from the embedded programme whilst this vote holds sway, while it still has authority, until we vote again. This is, at the end of the day, what parliamentary democracy is all about, regardless of the pros and cons of military intervention."

Labour, which recently indicated it could be prepared to back a fresh vote on extending air strikes into Syria, said that it would be calling on ministers to make a Commons statement on Monday about the role British pilots had played.

New Liberal Democrat leader Tim Farron said the involvement of RAF pilots in air strikes without the approval of Parliament was "a breach of trust with the British people" that would simply play into the hands of IS.

"They desperately want the West to attack them and to be seen to attack them. We are utterly playing in to their hands if we do this," he said. "For us to be involved in this at this stage, without the sanction of the British people through Parliament and without proper thought being given to the way in which we almost strengthen Isis by doing this, seems very wrong."

The Freedom of Information response said that UK military personnel were embedded with units of the US, Canadian and French armed forces taking part in international coalition operations against IS. The MoD said the British pilots involved flew intelligence, surveillance, reconnaissance and strike missions against IS. The first US-led air strikes on Islamic State targets in Syria took place in September last year.

RAF planes are already involved in surveillance flights and air-to-air refuelling operations over Syria in support of coalition strike missions.

Following last month's terror attack on British tourists in Tunisia, Mr Cameron and Mr Fallon indicated they could seek Commons approval for UK warplanes to join the air strikes as well.

Mr Fallon insisted the Government remained committed to seeking parliamentary approval before launching British air strikes on Syria.

"This is different. These are a handful of British pilots who have been embedded with American forces and are part of an American military operation for which the Americans have full approval," he said.