Prisoners smashed through their cell walls and staged a four-hour stand-off with guards, the BBC has learned.

Six inmates broke through the walls in the prison’s segregation unit and gathered in one cell at HMP Leicester.

It is not known what prompted the disorder, which happened in December, or how the men smashed the walls.

Conditions in the unit were described in a report last year as “poor” because of overcrowding.

Three-hour disorder

The Ministry of Justice (MoJ) said there were no injuries to staff or inmates and police were investigating.

Extra guards were drafted in to tackle the situation on 11 December, the Prison Officers Association said.

A spokesman said one prisoner started to smash his wall at about 22:30 GMT and was copied by others.

“In the space of three hours six prisoners had broken through walls within the segregation units. National resources were deployed,” he said.

In a national HM Inspectorate of Prisons report published in June, the category B prison’s segregation cells were described as “particularly poor”.

In a separate report on the prison from 2014, the unit containing six cells for prisoners who had been separated for disruptive behaviour, was said to be “nearly always full”.

“The accommodation used for segregation was not sufficiently robust, nor spacious enough to house all prisoners judged to need segregation,” it said.

It added: “The cells were in poor condition and had been damaged; the plaster had been torn off the walls and the concrete painted over.”

An MoJ spokesman said there were no injuries and there was no evidence it was an escape attempt, as external walls were not compromised.

“Once the situation was resolved, the offenders were transferred to other prisons as punishment and we contacted police, who are investigating,” he said.

“There was no disruption to the wider prison as a result of this incident.”