UK pilots embedded with coalition allies’ forces have been conducting air strikes over Syria against the Islamic State group, it has emerged.
This is despite UK MPs voting in 2013 against military action in Syria.
About 20 personnel, including three pilots, have been embedded with other coalition nations’ forces, including the US and Canada, the BBC understands.
Defence Secretary Michael Fallon defended the exchange of troops, saying it was “standard operating practice”.
However, there was criticism from Labour, UKIP and the SNP, and some within the Conservative party.
Tory MP John Baron said the personnel should be withdrawn as Parliament had “said no to military intervention”.
The MoD said personnel embedded with the US, French and Canadian armed forces had been authorised “to participate in coalition operations” and were under those forces’ chain of command.
UK pilots are not currently taking part in the region, the MoD said, but ministers would have been aware of their recent role – and the prime minister’s spokeswoman confirmed David Cameron had known.
Mr Fallon said it was “absolutely standard practice” to exchange personnel with allied forces, and had been “since the end of World War Two”.
He said there was “no mystery about that”, and “most people have known”.