Whitemoor Prison has a high number of Muslim inmates
A Prison Service report has expressed concern about problems with the high number of Muslim inmates at one of Britain's high-security jails.
A review of Whitemoor Prison in Cambridgeshire found staff were fearful of doing the wrong thing, "shifting the power dynamic towards prisoners".
The Howard League for Penal Reform said the report was "extremely disturbing".
The Prison Service says it will examine how to manage gangs and terrorist prisoners at the jail.
The report, written by the Prison Service's Directorate of High Security, was obtained by the Howard League under the Freedom of Information Act.
It found staff at Whitemoor Prison near March, Cambridgeshire, "appeared reluctant to challenge inappropriate behaviour, in particular among black and minority ethnic prisoners, for fear of doing the wrong thing".
"This was leading to a general feeling of lack of control and shifting the power dynamic towards prisoners," the report said.
"A wing itself felt particularly unstable with a general lack of confidence among staff."
The report said there was an "ongoing theme of fear and instability" around the prison and many staff believed a "serious incident" was imminent.
It said the "very high Muslim population" - more than one in four of the 500 inmates - appeared to be "leading to anxiety and apprehension among some staff".
"There is a danger of this leading to hostility and Islamophobia if it is not addressed," the report adds.
Andrew Neilson, assistant director of the Howard League for Penal Reform, which obtained the report under the Freedom of Information Act, said the findings were of concern.
"One of the things the report does flag up is that low grade prison officers feel unable to confront with sensitivity Muslim prisoners.
"And therefore they're not really aware whether these are criminal gangs - or criminal gangs with a darker side where radicalisation is also going on."
The report recommended an "intelligence assessment of the Muslim prisoner group of concern and their possible activities" and "more cultural awareness and diversity training".
Whitemoor governor Steve Rodford asked for the wide-ranging review after five prisoners committed suicide between November 2006 and December 2007.
A 14-strong Prison Service team carried out the investigation in February.
The Prison Service said a "programme of work" was planned "to increase mutual understanding between staff and prisoners", including a "development day for staff on the Muslim faith".
A Prison Service spokeswoman said: "Appropriate training and staff awareness are crucial in tackling radicalisation.
"The prison will continue to work closely with the Prison Service's Extremism Unit and the police to monitor and assess issues around extremism, and work will be undertaken to examine the management of gangs and terrorist prisoners within the prison."