The Chief Inspector of Prisons is writing to the Justice Secretary to raise “significant concerns” about the state of HMP Birmingham.
Peter Clarke has taken the step of issuing an urgent notification to David Gauke about the privately-run jail, following a recent inspection.
Known locally as Winson Green, the prison made headlines this week after nine cars were torched during an arson attack on the staff car park on Tuesday afternoon.
Two of the cars destroyed in the blaze reportedly belonged to members of Mr Clarke’s inspection team, but are not believed to have been deliberately targeted.
Inspectors were on an unannounced two-week visit to look at conditions in the jail.
Nobody has yet been arrested in connection with the attack, in which two masked men used an angle grinder to cut their way into the parking compound before dousing vehicles in accelerant.
Further damage was prevented after the men, one of whom was armed with a handgun, were confronted by two prison staff.
In a statement, Her Majesty’s Inspectorate of Prisons (HMIP), said: “Peter Clarke, Chief Inspector of Prisons, has decided to issue an Urgent Notification (UN) in relation to HMP Birmingham, following significant concerns raised by an inspection.
“A letter will be sent to the Justice Secretary in accordance with the UN protocol.
“HMIP will not release any further information about the HMP Birmingham inspection and Urgent Notification until the publication of the letter sent to the Justice Secretary.”
There is a set protocol governing the Urgent Notification process, which is used to flag up issues related to matters including conditions and treatment of inmates.
The chief inspector will be writing to the secretary of state within the next seven days, setting out the concerns and areas requiring improvement.
The governor of HMP Birmingham – a category B jail with capacity for up 1,450 inmates – will also be informed of the findings.
In December 2016, the G4S-run jail was rocked by the worst outbreak of rioting at an English jail in more than 20 years.
Inmates caused widespread damage after seizing control of four wings, and releasing 500 prisoners from their cells.
Seven men were later convicted of prison mutiny for their role in the rioting.
A G4S spokesman said: “We have not yet received a formal response following an inspection of HM Prison Birmingham.
“Therefore it would be inappropriate for us to comment further at this time.”
Richard Burgon MP, Labour’s shadow justice secretary, said: “Despite repeated damning inspection reports, the Conservatives have failed to get a grip on the prisons crisis which has now become an emergency.
“Failure to address this prisons emergency risks leaving the public less safe.
“The Government must urgently set out a clear plan and new funds to make our prisons safe and humane for prison staff and prisoners alike.”
The urgent notification system was set up last year by government ministers to rapidly tackle significant problems arising in jails.
The Justice Secretary will have 28 days to respond with a plan of action to resolve urgent and severe issues at the prison.
A Prison Service spokesman said: “We await the letter outlining the inspectorate’s findings and once received we will respond to the issues it raises.”