DAVID CAMERON faced calls yesterday to come clean over the extent of Britain’s secretive role in Yemen’s bloody civil war.

SNP Westminster leader Angus Robertson pressed the Prime Minister to admit that Britain was “effectively taking part in a war” without the support of Parliament.

Amnesty International revealed this week that the British government granted £1 billion worth of arms export licences for Saudi Arabia, which leads a coalition that is bombing Yemen in support of its ousted president Abed Rabbo Mansour Hadi.

The charity criticised ministers for signing off “large consignments of bombs and other munitions” despite evidence of human rights violations committed by the coalition in its bombing campaign.

Raising the issue at Prime Minister’s Questions, Mr Robertson said: “Thousands of civilians have been killed in Yemen, including a large number by the Saudi air force …using British-built planes with pilots who are trained by British instructors, who are dropping British-made bombs and are co-ordinated by the Saudis in the presence of British military advisers.

“Is it not time for the Prime Minister to admit that Britain is effectively taking part in a war in Yemen that is costing thousands of civilian lives and that he has not sought parliamentary approval to do that?”

Mr Cameron said British forces were providing training to Saudi pilots to “make sure that countries actually obey the norms of humanitarian law.”

But he insisted they were “not directly involved” in selecting targets, directing operations or carrying out strikes in Yemen.

Downing Street spokespeople did not deny British advisers were present in the operations room when raids were carried out.