The intelligence and security committee will seek details from the intelligence agencies about its contacts with Mohammed Emwazi, as reports circulated that British spies had previously detained him and may even have tried to recruit him.

Sir Menzies Campbell, an outgoing member of the committee, said he expected the committee to seek a report after the election.

He added that he had been totally unaware of the identity of the man dubbed “Jihadi John” but added the alleged contacts between MI6 and Emwazi had echoes of those with Michael Adebolajo.

Campbell said: “One of the difficulties here is that you cannot keep an eye on everyone all of the time and as the committee found in the case of Lee Rigby [who was murdered by Adebolajo] there is no doubt from time to time the security services have to prioritise those upon whom they are conducting surveillance.”

He said judgment was not possible without further details, but he expected the committee in the next parliament to launch an inquiry, or at least seek a report from the agencies.

He said the episode again raised questions about whether the agencies had sufficient resources. He pointed out the recent £130m increase in the security services budget of £2bn would not go far since it covered three agencies and a two-year timespan.

“If we are told constantly, and in my view with justification, that the nature of the threat is now so great that everything has got to be done to protect the citizens of the UK, then it does seem to me that we have got to once again look at the resources available,” he said.



He said extra money was not an immediate solution, but a responsible government would go out of its way to ensure that it had all the resources available.

Campbell said he was not surprised that the ISC has not been told the name of the suspect.

“Although the committee is entitled to some evidence about operational activities, by and large that is normally after these operations have concluded for the very obvious reason that you would not want the security services to give the committee a running commentary at any particular point of time,” he said.

Yvette Cooper, the shadow home secretary, said she had already asked whether it was right to weaken control orders and whether more money was needed to be put into the “Prevent” strategy designed to weaken the radicalisation process. She did not commit to an increase in the security services budget, adding that it was difficult to identify the biggest risks.

Asim Qureshi, research director of Cage, which campaigns on behalf of communities affected by the “war on terror”, said: “Like Michael Adebolajo, suffocating domestic policies aimed at turning a person into an informant, but which prevent a person from fulfilling their basic life needs would have left a lasting impression on Emwazi. He desperately wanted to use the system to change his situation, but the system ultimately rejected him.”

Downing Street refused to say whether it believed the man was Emwazi. David Cameron’s deputy official spokeswoman said: “We cannot confirm or deny anything in relation to intelligence. The point the prime minister would make which, we have said since we have seen the awful actions of these Isil [Isis] terrorists, is that we are absolutely determined to bring the perpetrators to justice. The police an security agencies have been working hard to do that.”

Asked whether Emwazi was known to the security services, she said: “I’m not going to get into the details of an ongoing police and security investigation.”

When asked if Downing Street had any concerns about Emwazi being named in the media, she said: “I think the prime minister would be concerned about information being put into the public domain at any time that might jeopardise an ongoing police and security investigation or the safety of British citizens.

“The point I would make is that there is an ongoing investigation. It is absolutely right that we allow the police and security agencies to do all they can to bring those responsible to justice and help keep British people safe.”