The Howard League for Penal Reform said a leaked report of an inquiry into Whitemoor Prison near March, Cambridgeshire, showed that Prison Service investigators had found problems which needed "urgent" attention.

One issue raised in the report was concerns about the increasing power wielded by "gangs" of Muslim prisoners, said the Howard League Conservative MP Malcolm Moss, who represents North East Cambridgeshire. He said he also feared that something was "seriously wrong" at the prison because a number of staff had raised concerns with him.

A league spokesman said the report showed that morale among Whitemoor staff was low - and Mr Moss said he had come to the same conclusion.

The report says that in January Whitemoor Governor Steve Rodford asked the Prison Service's High Security Directorate to conduct a "wide ranging review" of the jail.

It says the Governor's request came after five prisoners committed suicide at the jail between November 2006 and December 2007.

The report says a 14-strong team carried out an investigation at the prison in late February. "The review team found a number of recurring themes that were fed back from both staff and prisoners," said the report.

"Without doubt the stand-out issues were around poor communication and the rapid implementation of change.

"There is a clear need to provide staff with clear direction for Whitemoor, alongside consistent and timely messages.

"Staff need to feel more involved in the change process to increase buy-in and cooperation."