PRIME Minister David Cameron today vowed to put Jihadi John "out of action."

Mr Cameron hit out after being challenged over whether the security services could have done more to stop the ISIS terrorist Mohammed Emwazi, who has been named as the masked militant seen in Islamic State videos, slipping through the net.

He said: "When there are people anywhere in the world who commit appalling and heinous crimes against British citizens we will go everything we can in our power to find these people and put them out of action. That is the priority for me."

Mr Cameron said in the five years of working with the British security services he had found them to be "incredible impressive, courageous and effective in defending our country."

He said: "I think they make very good judgements on our behalf and I think the most important thing is to get behind them."

Mr Cameron revealed that British agents had saved the UK from several terrorist plots to kill on the streets of Britain.

He said: "All I can say is that even in the last few months their dedication and hard work has saved us from plots being carried out on the streets of the UK."

Cameron stood side-by-side with Nick Clegg as he announced new devolved power to Wales. It was the last joint press conference to be made by the pair after five years of coalition government before the general election campaigns really begin.