ISLAMIST extremists are holding Sharia trials in British prisons and grooming young Muslim inmates, a probe found.

Punishment beatings have been dished out and banned books have circulated, prompting security experts to seek a review of terrorist radicalisation in jails.

1 London Bridge terrorist Usman Khan was shot dead after killing two people on November 29th Credit: EPA

The issue is under scrutiny after Usman Khan, 28 — a Category A terrorist inmate freed on licence — killed two people at London Bridge last month before cops shot him dead.

One ex-prisoner at HMP Woodhill, Bucks, claims he was lured into a group pledging allegiance to IS.

MOST READ IN UK NEWS HUNTED DOWN 'Gun seller' arrested for supplying firearm that killed Matt Ratana Exclusive HAPPY MEAL McDonald’s worker who paid for lad’s meal has secretly bought food for MONTHS PANIC STATIONS Panic buying sweeps country AGAIN clearing Tesco, Asda & Morrisons' shelves WHERE WERE THE PARENTS? Sobbing toddler found wandering Hull streets completely ALONE NUMBER CRUNCH Covid infections NOT rising like 'nightmare projection' by top Gov experts SEE THE SPIKE Burnley now England's new Covid hotspot - so how does YOUR town compare?

He told The Times he found himself sitting in judgment at a cell-block court over two prisoners who had supposedly disrespected Islam by drinking alcohol.

The ex-head of Scotland Yard’s Counter Terrorism Command, Richard Walton, and Ian Acheson, who has led a review of jail extremism, said reforms to tackle the problem had ground to a halt.

Mr Walton added: “It is unsurprising radicalisation continues to be a significant challenge, owing to the success in recent years of convicting high numbers of Islamist terrorists for plotting attacks.”

Two women whipped by masked Sharia law enforcer after being caught with men in Indonesian hotel raid