AN influx of inmates at British jails following the country's riots has sparked a gang culture behind bars, a prison boss says.

Two thirds of the more than 1500 people charged over the August violence - in which five people were killed, property was damaged and businesses looted across England - have been remanded in custody, pushing the country's prison population to breaking point.

Already the lockups have resulted in a rise in the number of prison incidents, Chief Inspector Nick Hardwick said.

"There have been tensions between prisoners, some potentially serious incidents and significant numbers of young people placed on self-harm prevention procedures," Insp Hardwick said, his comments published throughout British media.

"There have been some quite serious incidents of groups fighting, fights between individuals and gangs reconfiguring.

"Some young people who previously did not have gang affiliation have joined for self-protection. New gangs have also been established."

At one London young offenders institute the trouble led to the destruction of a gymnasium, while at another centre inmates were able to enter a restricted roof space from where they refused to return to their cells.