A prisoner has been badly injured in a disturbance that involved 260 inmates and closed four wings of a privately-run prison in Birmingham.

The Prison Officers Association (POA) initially confirmed two wings of HMP Birmingham were affected, but later confirmed the trouble had flared to two further wings.

They said "all staff have been accounted for" across the four wings."

In a statement, West Midland's Police said the incident "is contained within the prison walls", and its officers are "offering a visual reassurance around the perimeter."

They added: "It's understood a set of keys giving access to residential areas was taken from an officer and that offenders have since occupied some blocks and exercise facilities.

"No keys to perimeter access points were taken."

A source told ITV News the dispute began over TVs not working.

Shadow justice secretary Richard Burgon said the incident is "hugely concerning."

The Victorian category B prison is run by G4S and can hold 1,450 adult remand and sentenced male prisoners.

A G4S spokesman said the Prison Service has taken over the management of the incident.

West Midlands Ambulance Service said they were called to the prison at 12.23pm and currently have a hazardous response team at the scene.

Prison affairs academic and blogger Alex Cavendish said a source inside the prison told him the trouble started with lights being broken and inmates controlling fire hoses.

He said: "I am hearing there is a very badly injured casualty (prisoner), and the prisoners are throwing computers out of the OMU window - destroying records."

Mr Cavendish said an inmate had snatched a set of keys from a prisoner officer while he being put in his cell, as is procedure during an emergency.

The prison officer was threatened by what appeared to be a used syringe and the keys were taken while he was distracted.

He described the incident as "probably the most serious riot in a B category prison since Strangeways went up" in 1990.

"It is a very serious situation and I think the fact they have now accessed the key offices like the offender management unit - that is where all the offender records are.

"If they destroy all of those records it is going to take months or even years to rebuild the information."

The POA said all staff were accounted for and none had suffered any injuries.

It is understood around 400 inmates are thought to be in the trouble across the four prison wings.

A 'Tornado' squad has been called in to contain the situation.