Independent inspectors questioned the effectiveness of the British prison unit holding terrorists.
From 2018 to 2019, Frankland Prison in north-east England held five of the country’s most dangerous extremists.
They lived in isolation, away from the rest of the jail population, in a high-security separation unit.
Three such units were planned, intended to hold up to 28 inmates regarded as a radicalisation risk to other prisoners.
But the unit at Frankland is the only one functioning and monitors spoke of prisoners refusing to obey the regime in the violent and claustrophobic unit, according to a new report.
“Is the separation centre, initially conceived to be one of several, now viable in the successful management of these prisoners?” said the most recent annual report of the lay Independent Monitoring Board for Frankland.
“Patterns of behaviour seem to have become entrenched, with concerted non-co-operation with the regime offered, and, worryingly, there has been a serious assault on a member of staff,” it said.
Separation units were set up on the basis of a report in 2016 by former prison governor Ian Acheson into extremism in prisons.
A court this month heard how Khairi Saadallah, 26, who murdered three men in a knife attack last year, sought the company of prominent extremist preacher Omar Brooks while serving a previous sentence.
Brooks was connected to the banned terrorist organisation Al Muhajiroun, which was linked to helping dozens of young Britons travel to Syria to join ISIS.
The government said the units would be for those who “seek to poison the minds of others”, but Frankland is now the only such centre operating.
A report on their effectiveness commissioned by the government in 2019 concluded that moving some of the most influential extremists to separation units may have reduced disruption among other prisoners.
But it said those men also stopped taking part in rehabilitation work in the specialist centres, which meant they could not be reintegrated into the mainstream population.
It said officials need to consider whether they were “intended as a short-term measure to disrupt the immediate influence of a prisoner or whether they are viewed as a long-term location”.
The UK's justice ministry declined to say how many people are held in the Frankland separation unit but said that most extremists could be managed within the mainstream prison population.
Terrorists accounted for 243 prisoners in Britain in July 2020, an increase of 24 compared with the previous year, with two thirds of them holding extreme Islamist views.
“These centres stop the most influential extremists from spreading their poisonous ideology and it would defeat the object if we put in offenders who can be managed safely elsewhere,” a justice department representative said.