Details have emerged of a private briefing between the government's most senior counter-terrorism official and MPs in which he warned of the dangers of radicalisation among Muslim prisoners and admitted that CIA agents were operating in the UK.
Charles Farr, the head of the Home Office's office of security and counter-terrorism, told MPs the 8,000 Muslim inmates in England and Wales represented "a very significant group".
"We know that once they get inside prison there is a danger that they will be radicalised ... there is an additional risk that, for entirely legitimate reasons, people can get converted in prison to Islam. We are very aware of the risks," he said.
On the issue of Islamist radicalisation in prison, he revealed his unit had to help a cash-strapped prison service find enough money to develop a counter-terrorist programme, including the creation of an intelligence infrastructure.
That unit, he said, had made some inroads in tackling extremism in prisons. "It is not yet a success story but it is a story of real progress," he said, and added: "When they get back into the community what are we going to do about that?"
During the in camera evidence session to a sub-committee of the Commons home affairs select committee, Farr also confirmed there were CIA agents operating in Britain and that Britain had a "very close" relationship with the US intelligence community.
Asked if CIA agents and other "outside organisations" were working in Britain, Farr replied: "Most certainly, yes. Are they declared? Yes. They are in regular dialogue with our agencies here. The cornerstone of this is the American relationship.
"Why? For two reasons, I think, above all: because of the huge American capability that can be brought to bear on counter-terrorism, and has been since 9/11.
"Secondly ... because people who pose a threat to this country are six hours away from the eastern seaboard, something which the Americans are acutely aware of, as are we, and therefore take a very close interest in."
Farr, who rarely appears publicly, also disclosed that last year's visa ban on the Islamist preacher Sheikh Yusuf al-Qaradawi, was not straightforward. He described Qaradawi as "one of the most articulate critics of al-Qaida in the Islamic world" despite his antisemitic and homophobic views. He said the ban was still a current issue.
The redacted transcript of the unannounced evidence session, which took place in February, was vetted by Farr before it was published as an obscure annexe to a Commons home affairs select committee report on counter-terrorism published over the summer.
On prisons Farr said that there was a "very large, complicated counter-terrorist programme" run by the National Offender Management Service under a strategic framework provided by his office.
"We are funding it. They do not have enough money so we have transferred some of our programme budget, and it is a good thing that we are able to do that, into the Ministry of Justice to enable them to get it off the ground," he said.
Farr said Muslim prisoners constituted 12% to 13% of the total prison population. He said that there was a direct relationship between criminality and radicalisation that "greatly interests us", with those with non-terrorist criminal records finding terrorist networks a refuge from the isolation and alienation that they face in the community as a result of their criminal activities. For this reason the group of 8,000-plus Muslim prisoners were more vulnerable to radicalisation than many others.
Farr also said the Home Office's research, communications and information unit, which advises on the nature of the terror threat, only has a staff of 35 from across government to challenge the output of 4,500 "incessant" Islamist terrorist websites around the world.
The head of the office of security and counterterrorism on:
Challenging extremists Farr emphasised that he was not interested in criminalising those with extremist views that fell short of violence.
Muslim attitudes The Home Office, said Farr, had been too reliant on commercial polling to gauge changing attitudes in the Muslim communities."
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Qaradawi "I think for any government, and I really passionately believe this, this is a real problem," said Farr. "If we refuse him a visa people will come back to us and say, 'Hang on a moment. This person is coming here to speak against the organisation which most threatens you. Surely you need to operate within a degree of latitude which allows that.' I am not saying that is a compelling argument.".