Yusuf Rahim — a man who will be familiar to most by his real name, Levi Bellfield

Friday morning in Wakefield Prison and Yusuf Rahim joins 60 other Muslim prisoners as they head to the jail’s gym to say their prayers. If nothing else, it is a chance to get out of his cell and take a break from the normal routine.

The same goes for the halal food the 47-year-old is served every mealtime — Rahim is particularly partial to the spicy vegetable curry — an improvement on the normal prison fare.

And there is one other advantage to his new-found religion. Because, as one of Britain’s most reviled murderers, he is banking on his Muslim ‘brothers’ providing him with some level of protection during his time inside.

At least that’s what Rahim — a man who will be familiar to most by his real name, Levi Bellfield — hoped would happen when he converted to the Muslim faith not long after being sentenced to life for the murder and rape of schoolgirl Milly Dowler.

‘He found out a paedophile had been slashed in Wakefield and thought he would be next: he was a marked man after he was convicted,’ revealed his sister Ann-Marie Bellfield. ‘He said they were good boys and would look after him ... he got friendly with Islamic guys and didn’t have a problem.’

Given the character of the man, few will be surprised to learn that Bellfield’s religious conversion — he reportedly refers to Islam as ‘this beautiful faith’ — was motivated by cowardice and self-preservation.

But it also shines a spotlight on a much wider issue that is causing widespread concern across government and beyond.

In recent years, the number of Muslim prisoners has increased dramatically. Ministry of Justice figures show a rise from 6,571 in 2004 to 12,255 a decade later, meaning that Muslims now account for almost 15 per cent of all inmates.

In high security jails, the figure is higher still — one in five; while in one Category A establishment, almost half are Muslims.

Taken on its own, the disproportionate numbers of Muslims being jailed is in itself cause for concern (Muslims comprise roughly 5 per cent of the population of England and Wales).

But what is particularly worrying the authorities is the potential it offers for radicalisation.

As the number of Islamist extremists locked up for terror offences increases, so they are finding fertile ground among fellow prisoners. Indeed, it is claimed that some are deliberately getting custodial sentences so that they can target this pool of disaffected young men.

In turn, there is growing evidence of the spread within prisons of Muslim gangs who wield so much power that other prisoners feel coerced into converting or doing as they bid in other ways.

‘If our prisons are going to be filled with more terrorism offenders, then I think they will also get even more full with radicalised individuals,’ warns Jonathan Russell, head of policy at counter-extremism think tank Quilliam.

‘There is a significant danger that our prisons will become net exporters of extremism, when, surely, if we are arresting terrorists, they should be net reducers.

‘And if we don’t get it right, the very real danger is that when people come out they will be further radicalised and further hardened to commit violence.’

Indeed, so pressing is the problem that the Government has announced it is considering the possibility of setting up ‘jihadi jails’ — prisons which solely house Islamist extremist terrorists.

Last Monday, Mr Cameron hinted at this radical new approach as he described tackling religious extremism as the ‘new front’ in prisons.

‘We have about 1,000 prisoners who have been identified as extremists or vulnerable to extremism,’ he said. ‘Some of these individuals are preying on the weak, forcing conversion to Islam, and spreading their warped view of the world.

‘I am prepared to consider major changes, from the Imams we allow to teach in prison to changing the locations and methods of dealing with prisoners convicted of terrorism.’

Pictured are the Muslim extremists who killed Lee Rigby - Michael Adebolajo (left) and Michael Adebowale

Quite what is behind the rise in the number of inmates within the prison population generally who identify themselves as Muslim is not entirely clear.

One factor is that if you are young and come from a poorer background, you are more likely to come into contact with the criminal justice system.

The Muslim population in Britain is, generally, younger and disproportionately concentrated in lower socio-economic groups. The upshot is a Muslim prison population growing faster than the Muslim population at large.

New figures obtained in the past few days from the Statistical Unit at the Ministry of Justice under a Freedom of Information Act request show that out of 88,000 prisoners in June 2015, 12,660 were Muslims.

Increases have occurred across the country. For example, in five years the number of Muslim prisoners at Pentonville prison in North London increased from 240 to 377. At Wormwood Scrubs, West London, there are 372 Muslims — up from 284; while at The Verne, in Dorset, the numbers increased from 84 in 2010 to 225 last year, a surge of 167 per cent.

But the highest proportions of Muslim prisoners are to be found at the country’s eight top security jails. Figures show that 1,229 out of 5,885 inmates, or 20.8 per cent, are Muslim. That is an increase of 23 per cent in five years.

Belmarsh prison in London has the most Muslim inmates, 248 of 868 — or more than 28 per cent.

But proportionately by far the highest is Whitemoor prison in Cambridgeshire, where roughly 44 per cent follow the Islamic faith. It held 199 Muslims in 2015 out of an official population of 447.

Caged inmates include rapists, killers and terrorists, among whom is Zia Ul Haq, 35, of Wembley, London, who was jailed for plotting to bomb a London Tube tunnel and set off a radioactive ‘dirty’ bomb.

Of course, there is no reason why a large grouping of Muslim prisoners per se should cause any more problems than if they were, say, Christian. But staff at Whitemoor say that such is their gang-like behaviour that they fear it is putting the safety of the institution in jeopardy.

‘In Whitemoor, we have a number of different Muslim groups: all are ultra religious, very insular and can be very intimidating,’ one staff member told the Mail, speaking on condition of anonymity. ‘There are radical groups on all three wings. They follow a very strict interpretation of Islam. They pray five times a day, follow a strict diet and do not mix with any other prisoners. They don’t watch television or play on computer games.

‘You see what’s going on and think that some of these people are being indoctrinated by some very strong personalities.’

These gangs effectively run their wings — meaning that other prisoners are left with a difficult choice as to how they should react.

Friday morning in Wakefield Prison and Yusuf Rahim joins 60 other Muslim prisoners as they head to the jail’s gym to say their prayers (file photo)

‘Every new prisoner will be targeted by the religious gangs,’ he says. ‘They will tell him to join his “brothers”. They will offer him protection and support providing he prays five times a day and follows their version of Islam.

‘They will tell him that they are not interested in his crime providing he promises to be a good Muslim.

‘They will offer the same deal to anyone; it’s a case of “that was your previous life and that doesn’t interest us”. I would say about half of the Muslim groups on a couple of the wings are converts to Islam.’

And he added: ‘There is some sort of incident every day in Whitemoor involving the Muslim groups. It might be a row about the food or someone claiming their prayer time has been interrupted.

‘These can be violent episodes, and sometimes they are concocted as some sort of power play, which is directed not just at the other prisoners but the guards as well.’

Tensions at the jail were also highlighted in a report based on a series of interviews with inmates by Alison Liebling, a professor of criminology at Cambridge University in 2011.

Some told researchers they were bullied into changing religion, while those who resisted said they were too scared to cook bacon in communal kitchens in case it caused offence.

Others claimed the jail was a ‘recruiting ground’ for extremism, as young inmates were ‘in awe’ of convicted terrorists held there.

The report added that there was considerable ignorance and confusion about the Islamic faith, meaning ‘those with extremist views could fill a gap in knowledge with misinformation and misinterpretation’.

This is of particular concern given the increased number of Islamist extremists being jailed for terror-related offences.

Last month, Nick Hardwick, the outgoing chief inspector of prisons, warned: ‘There are undoubtedly a small number of very dangerous men motivated by a religion or ideology who are trying to recruit other people so they will go on to commit offences linked to that ideology or religion.’

It is a point echoed by Steve Gillan, general secretary of the Prison Officers’ Association. ‘The dangers of gang cultures and radicalisation of young Muslim men is a real concern, as within our prison system it can have a destabilising effect,’ he said.

‘Added to this, the Government has cut prison officer numbers by 25 per cent since 2010. This is a recipe for disaster at a time when the UK is under a huge threat from terrorism.’ Beyond the very real risks of radicalisation, prison officers are also having to deal with the fall-out caused by tensions between Muslim gangs and other inmates.

‘These gangs use their faith as a cover for violence and intimidation, threatening non-Muslims and pressuring them to convert to Islam.

‘I have got many prisoners who are so fearful of Muslims that they feel they need to form alliances with them for protection,’ one prison governor recently revealed.

‘There are some vulnerable young boys who will have converted because they are afraid. I think it is more a gang issue than radicalisation, but this is a big issue.’

Joe Chapman, a former prison officer who now acts as a prison law consultant, believes the problem of so-called ‘convenience conversions’ is on the increase.

‘This job takes me to 40 or 50 prisons over the year, throughout the country,’ he said. ‘It has become obvious to me that it’s a growing problem.

Jordan Horner was jailed for targeting people drinking alcohol, couples holding hands and women deemed to be dressing ‘inappropriately’ in 2012

‘About half a dozen of my clients have directly reported problems with being forced to convert — those who weren’t Muslim when they came in, and those who were and have been forced to look at more radical ideas about their faith.’

One young woman whose brother is serving a lengthy sentence in a top security prison in England told how he was being bullied by members of a Muslim gang who were trying to force him to convert to Islam.

‘He just looks like a broken man,’ she said, again asking not to be identified. ‘He’s tearful on visits, and I’m just really scared for him. He’s been physically assaulted. He’s had black eyes. In the showers, he got threatened with a knife.

‘He’s not going to back down. He’s not going to convert for anyone. He just spends his time hiding in his cell. He’s got at least another five years to serve. I don’t know how much longer he can hold out.’

Another serving prisoner told the Mail: ‘Some people really struggle when they come in to prison. They will try to find some support — and the Muslim groups offer that. A lot of black men in their early 20s who are in on violence or drug charges are targeted.

‘They would maybe have been part of gangs for a long time. But in prison, they’re on their own. I’ve seen guys who’ve been beaten up or bullied, had their fags nicked and their cells turned over, that sort of thing, and then they’ll be befriended by some of the Muslims.

‘Then the guy will put in a formal request saying that he wants to change his religion. He might have a meeting with the governor and he goes through the process of becoming a Muslim. Everyone knows why they are doing it — it’s not as if they have suddenly found God.’

As for those who refuse, such is the influence of these gangs that in some prisons they have started to impose a ‘protection tax’ on anyone who does not follow Islam.

The tax, called jizya, is reported to have been levied by gangs of Islamist extremists at Belmarsh, Long Lartin, Woodhill and Whitemoor prisons.

According to evidence supplied to a government-appointed team investigating extremism in jails, inmates claimed to have been bullied and threatened with violence unless they made payments with phone cards, food, tobacco or drugs.

Some of the alleged victims said they were told to arrange for friends and family on the outside to transfer money to nominated accounts.

To that background, there are growing calls for the Government to act quickly and decisively.

The appointment of Peter Clarke, Scotland Yard’s former head of counter-terrorism command, as the new chief inspector of prisons is seen as a sign that Justice Secretary Michael Gove is preparing to step up the fight against extremist gangs in jail.

Mr Gove has also appointed Ian Acheson, a former Home Office official, to carry out the aforementioned investigation into extremism and radicalisation in prisons and to develop ways of tackling the problem.

As for the Prime Minister’s suggestion last week that extremist Islamist prisoners could simply be segregated from the wider prison population, if past history is anything to go on, such a move would almost certainly be challenged through the courts.

Last year two terrorists linked to Al Qaeda successfully brought a case after being kept in solitary confinement.

The Supreme Court ruled that Kamel Bourgass, who murdered a policeman and plotted to spread the poison ricin on the streets of the UK, and Tanvir Hussain, jailed for a plot to blow up transatlantic planes, had been segregated ‘unlawfully’ in jail.

This was despite evidence that the pair had bullied fellow inmates in a bid to radicalise them. Hussain, it was claimed, had been preaching through his cell window ‘in a determined attempt to convert non-Muslim prisoners to his own interpretation of Islamic ideals’.

As the Mail revealed this month, the pair received more than £75,000 in legal aid to successfully challenge their treatment in court.