British pilots have taken part in air strikes against Islamic State militants in Syria, the defence ministry said on Friday, angering some lawmakers who two years ago refused to back military action there.
The ministry said pilots had taken part in Syrian missions on behalf of its allies, the United States and Canada, and were "effectively operating as foreign troops".
Prime Minister David Cameron, who knew of the pilots' role, failed to get approval from lawmakers in 2013 for military action in Syria. Britain conducts regular attacks in neighbouring Iraq.
"There is an element of sophistry going on here ... at the very minimum, an insensitivity to parliament's will," John Baron, a lawmaker from Cameron's Conservative Party, told BBC radio.