Radical preacher Abu Hamza is held at Belmarsh Prison
"Extremely high" levels of force are used to subdue prisoners at Belmarsh high-security jail, an inspection report has revealed.
Since the last inspection of the south London prison the number of inmates who said they had been victimised or intimidated by staff had increased.
One in five prisoners had been involved in violence, the report said.
The National Offender Management Service said there were "inherent complexities" in running the prison.
Chief Inspector of Prisons, Dame Anne Owers, said although security flaws had been tackled since the last inspection it had been to the detriment of prisoner care.
She said: "The overall conclusion of this inspection was that a predominant focus on security, to address some apparent weaknesses, had led to a lack of attention to prisoner care and rehabilitation.
"Those areas now need equally strong and robust management or staff too will see them as less important parts of their role."
Belmarsh is home to 66 high-risk prisoners.
A fifth of inmates are Muslim and the prison houses radical preacher Abu Hamza.
The report found that in one outbreak of violence, groups of Catholic and Muslim prisoners did battle in the jail's high security unit.
Phil Wheatley, director general of the National Offender Management Service, said: "The chief inspector rightly recognises the complexity inherent in running a prison like Belmarsh which operates as a local prison while also holding Category A prisoners, who must be held under appropriate security to ensure the public is protected."