HMP Birmingham riot: 240 prisoners being moved after riot
Up to 240 prisoners are being moved out of HMP Birmingham following a 12-hour riot at the jail.
Inmates took over four wings, started fires and gained access to medical supplies as they rampaged in the prison. One man was taken to hospital.
Friday's disturbance has been described by the Prison Officers' Association as the worst since the Strangeways jail riot 26 years ago.
Justice Secretary Liz Truss said there would be a "thorough investigation".
Rioters would "face the full force of the law," she added.
UK prisons chief Michael Spurr said there were "serious problems" in jails that would not be solved immediately.
The Ministry of Justice said riot teams restored order to all four wings of HMP Birmingham just after 22:30 on Friday.
The disorder was understood to have involved up to 600 inmates.
Two wings suffered "superficial damage" with more serious damage caused to two others.
G4S is in control of the jail and the cost of the damage will be borne by the firm, the BBC understands.
"Our teams have worked tirelessly throughout the night to assess the damage caused, start the process of clearing up and capture any evidence that could be used by West Midlands Police for any subsequent prosecutions," a G4S spokesman said.
"This disturbance is rightly subject to a thorough investigation and we are working openly and transparently with the Prison Service and other relevant authorities to understand the causes behind it."
The Ministry of Justice said: "The prison remains calm and ordered with additional staff on site to offer support.
A "limited regime" is being offered to inmates not involved in the disturbance, the spokesman added.
Prison visits have also now resumed.
Mike Rolfe, national chairman of the Prison Officers' Association, said more than 30 staff had left the Winson Green prison in recent weeks. He compared the trouble to the notorious Strangeways riot in 1990.
"We've been warning for a long time about the crisis in prisons and what we are seeing at Birmingham is not unique to Birmingham, but it certainly would seem that this is the most recent worst incident since the 1990 Strangeways riot," he said.
Ms Truss said: "I want to pay tribute to the bravery and dedication of the prison officers who resolved this disturbance.
"This was a serious situation and a thorough investigation will now be carried out.
"Violence in our prisons will not be tolerated and those responsible will face the full force of the law."
Analysis: BBC Home Affairs Correspondent Danny Shaw
As the investigation and clear-up operation get under way at Birmingham Prison, the immediate concern for officials will be the risk of "copycat" disturbances.
Many jails are volatile places, with violence never far from the surface.
Reports of the rioting and rumours about how it all began could encourage others: it may be no coincidence that this is the third serious prison disturbance in six weeks after Lewes and Bedford.
The other main consequence of the damage is that it'll put a number of cells out of use at a time when capacity is already stretched.
Last week, there were around 1,200 spare prison places across England and Wales - that may seem like a lot but, spread across a large geographical area with different categories of prisoner to accommodate, it doesn't leave much slack in the system.
The BBC understands that one prisoner was hurt during the riot and taken to hospital with a fractured jaw and broken eye socket.
Prison wings are now being inspected to assess the full scale of the damage after prisoners took control of the category B prison on Friday morning.
Rodger Lawrence, chairman of the Birmingham Prison Independent Monitoring Board, said his members had not seen anything of concern during a visit earlier this week, but said the riot "didn't come as a complete shock" as there had been "a build-up of frustration" over prison conditions.
Michael Spurr, who is chief executive of the National Offender Management Service Agency, said overcrowding, reduced staffing and drugs had put pressure on prisons.
"On a day-by-day basis governors and staff keep prisons safe and manage a very difficult population extremely well," he told BBC News.
"Yes, there are assaults, there is too much violence, but we are tackling that.
"It will take some time but events in prisons such as yesterday do happen on occasions."
He said a £1.3bn investment in new prisons over the next five years, which includes plans for more prison officers, drug tests for inmates on entry and exit from prisons, and more autonomy for governors, would help tackle the issues.
"Over the coming months and years, we will turn it around," he said.
Trouble flared after an officer was "rushed" by inmates at about 09:00 on Friday.
Violence quickly escalated and due to the scale of the disturbances the Prison Service took over the incident and specialist Tornado units were deployed to regain control.
Prison units from across the country were also drafted in to assist.
During the disturbance, the BBC was contacted by several men claiming to be prisoners at the jail, who said poor conditions were behind the disturbance.
The men, who said they were calling from inside HMP Birmingham, cited inadequate staff numbers, poor healthcare and nutrition.
They said being on "lockdown" in their cells all day was a major factor that contributed to the trouble.
HMP Ashwell riot
BBC Home Affairs correspondent Danny Shaw believes that although the riot at HMP Birmingham was "clearly very serious", it may not be the worst since Strangeways, as the Prison Officers' Association has claimed.
He said: "In April 2009, there was a riot at Ashwell prison in Rutland involving 400 inmates.
"It caused such extensive damage to three wings in the old part of the jail, the entire prison closed permanently in January 2011 because the cost of repairs would have been too great."