London, UK - Officers are "insufficiently trained" to combat radicalisation at a major jail housing prisoners on terrorism offences, says the prisons watchdog.
Chief prisons inspector Anne Owers said Muslim chaplains were doing "excellent work" at Belmarsh in south-east London but needed more support.
She warned prison officers may not fully understand the complexities of tackling terrorism recruitment.
Efforts to counter extremism risked alienating Muslim prisoners, she said.
Belmarsh, partly built to house IRA prisoners, now holds the majority of those awaiting trial on terrorism offences.
However, the great majority of the 200 Muslim prisoners at the jail are inside for ordinary criminality and are not associated with those being held under special high security conditions.
In the report, Ms Owers said Belmarsh had improved thanks to efforts by managers to incrementally change its culture rather than attempt a sequence of quick wins.
But she warned staff needed more support to perform "the delicate task" of countering the risk of radicalisation from terrorism convicts - while at the same time avoiding alienating the general Muslim inmates.
"This group [terrorism prisoners] provided a challenge to staff and managers, both in relation to their own approach and behaviour, and the risk that they might influence other disaffected prisoners," said Ms Owers.
"There was clearly a concern that these minority views should not spread.
"But conversely there was a real danger that the alienation of Muslim prisoners in general, and the suspicion with which they perceived they were treated, would in fact feed radicalisation."
'Shorthand thinking'
In evidence before MPs in November last year, Belmarsh's governor Claudia Sturt said she did not want her staff to fall back on "shorthand thinking" which would lead all Muslims prisoners to be labelled extremist.
But Ms Owers' report waned that actions by officers risked being interpreted by disaffected Muslims as "deliberately provocative". Some prisoners had already accused female officers of "inappropriate behaviour", said the report.
She warned against wrongly interpreting conversions to Islam inside the jail, or gatherings for communal prayer, as signs of a threat or evidence of radicalisation.
She praised the two full-time imams at the jail, and the support they got from governors, but added that less than half of the Muslim inmates felt they were treated with respect.
"These are very important and difficult issues," said Ms Owers. "It was not apparent that all staff understood the complexities within and around their Muslim population, or were able to establish effective and appropriate relationships with them.
"This is something that requires attention throughout the Prison Service, though it is particularly acute at Belmarsh."
Phil Wheatley, head of the National Offender Management Service, said he was pleased that Belmarsh had made progress
"I would like to congratulate the governor and her staff for delivering such notable improvements," said Mr Wheatley.
"Their achievement is all the more creditable given that Belmarsh is a challenging environment with its diverse and often difficult prisoner population including those who require the very highest levels of security."