Correctional facilities in the United Kingdom are increasingly a recruitment ground for Islamic extremists who use their faith to gang up on nonbelievers and force some to convert, a top prisons inspector told the U.K. media Monday. Nick Hardwick, the chief inspector of prisons, told The Times of London that Muslim gangs have increased their influence in the country’s jails and that it should be a bigger concern to leaders than the radicalization of British citizens.

"There are undoubtedly a small number of very dangerous men motivated by a religion or ideology who are trying to recruit other people so they will go on to commit offenses," Hardwick said, according to the Times. “You do have Muslim gangs, but the point about it is, it is a gang.”

He added: “That [it is a gang is] more important than it is Muslim. There might be pressure to join up, but how real that conversion is, is the big question.”

There are approximately 12,600 Muslim inmates in England and Wales, according to the Times. Believers constitute about half of the inmate population at the Whitemoor high-security prison in Cambridgeshire and nearly 40 percent of the inmate population Long Lartin maximum-security prison in Worcestershire.

Muslim prison gangs use faith as a proxy for intimidation and violence, Hardwick said. Some conversions to Islam are genuine, he added, but many are seen as "convenience conversions" by prisoners seeking protection from violence. Hardwick said U.K. Justice Secretary Michael Gove will likely increase efforts to fight extremist gangs in the country’s prisons.

Some prison employees have previously reported the increase of extremism in U.K. correctional facilities.  Muslims have been accused of celebrating news of the deaths of British servicemen and referring to white Brits as “white trash,” according to a report by the Daily Mail. Hardwick, who decided not to apply for a second five-year term as prisons chief inspector, will be succeeded next month by Peter Clarke, Scotland Yard’s former head of counterterrorism, according to a report by Sputnik International.