Muslim inmates in many of Britain’s high security prisons are forcing non-Muslims to pay a “protection” tax if they refuse to convert to Islam in jail.

The ‘tax’, known as ‘jizya’, is described in the Koran and is currently being enforced by ISIS in Iraq and Syria. Some alleged victims in prison said they were instructed to arrange for friends and family on the outside to transfer money to nominated accounts.

The findings were made by a government-appointed team investigating extremism in prisons. They were told some radical Muslim inmates are enforcing the jizya in four of Britain’s largest prisons: Belmarsh, Long Lartin, Woodhill and Whitemoor.

The four ‘category A’ institutions have a total capacity of 2,633 inmates, housing the most dangerous criminals – including terrorists.

The general secretary of the Prison Officer’s Association (PAO), Steve Gillan, said the level of Islamist extremism and radicalisation in jails was rising, with many non-Muslims facing intimidation and attacks for refusing to convert.

“People at times are bullied and intimidated and harassed into becoming a Muslim and, if they don’t, are attacked,” he told The Sunday Times.

Adding: “There is a massive issue about radicalisation and extremism and, to be fair, the prison service is trying to address it . . . Will it go away? No. I think the assumption is that it will get worse.”

A Whitehall source said:

“[The imposition of jizya] shows the extent to which Islamist extremism in prisons is becoming a problem when you have inmates seeking inspiration from the likes of Isis to intimidate and bully non-Muslims into paying for their safety. “It sets a dangerous precedent and sends a message to non-Muslim inmates that Muslims are going to run the prison according to their own rules and sharia [Islamic law].”

In September this year, there were 12,622 Muslim in UK prisons representing 10.8% of the prison population, while Muslims form just 5% of the general population.

In October, Breitbart London reported on a government report warning that within the UK’s first majority Muslim prison, non-Muslim inmates are being pressured to convert to an “Islamic protection racket” which forms the largest “power block” in the jail.

A groundbreaking study published in 2012 examining the relationship between staff and inmates at Whitemoor prison in Cambridgeshire found some prisoners had been forced to convert to Islam.

“Some prisoners and staff wrote about how the decision to convert to the Muslim faith was influenced, or forced, by other prisoners,” said the report, co-written by Alison Liebling, professor of criminology at Cambridge University.