Increased security at HMP Birmingham after riot

G4S, which runs the prison, said HMP Birmingham has undergone a number of significant changes since the 2016 riot

Security measures have been strengthened at a prison following a riot involving 500 inmates.

Prisoners took control of four wings at HMP Birmingham in December 2016.

G4S, which runs the prison, said there had been a number of changes to prevent something similar in future.

It comes after ITV said it had seen parts of a government investigation into the riot, which said guards at the prison were "worn down by chronic staff shortages".

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Stolen keys were used to free the hundreds of prisoners from their cells on 16 December, before inmates threw TVs out of windows, built bonfires, pelted staff with missiles and paint and used an injured prisoner as "bait" during the disorder.

At the time, the Prison Officers' Association described it as the worst disorder since the Strangeways disorder 26 years earlier.

Six inmates were jailed for their part in the trouble last September. Nine others were cleared of prison mutiny, but some admitted or were found guilty of other offences following the disturbance.

Four wings of HMP Birmingham were taken over in a 15-hour disturbance, Birmingham Crown Court heard

Jerry Petherick, managing director for G4S custodial and detention services, said: "It is clear that there were lessons to be learned following the unrest, and the prison has undergone a number of significant changes including the refurbishment of the damaged wings, investment in new technology and the strengthening of external security measures in the Victorian part of the prison."

A Prison Service spokesman said the government was tackling issues at prisons, recruiting an additional 2,500 prison officers.

"There is more to be done but we are committed to making sure prison officers can focus their efforts on turning around offenders' lives," he said.

The disturbance, to which prison officers from other sites were called, lasted 15 hours