Inspector: Brixton jail plagued by drugs, gangs and violence

In one of her most critical reports in recent years, Anne Owers also said the jail was infested with vermin and overcrowded. Inmates who shared a cell were forced to eat with an unscreened lavatory only feet away.

Other problems included a lack of vocational training for prisoners to help them get jobs after release and the excessive time they had to spend in cells because of a lack of alternative activities.

The only positive developments were improvements to education, work on race and diversity and the "energetic" attitude of the prison's new management team. Despite these, Ms Owers expressed grave concern about the jail, which houses 800 prisoners, and singled out the failure to curb the flow of drugs.

She blamed the absence of sniffer dogs, a lack of random or voluntary drug testing and "insufficient suspicion" by staff.

The quantity of drugs was "feeding violence and gang cultures", leading to more than half of inmates reporting they have felt unsafe.

Efforts by staff to tackle gangs were "underdeveloped". Ms Owers added: "Brixton prison exemplifies all the problems of our overcrowded prison system. It has cramped and vermin-infested buildings, no workshops to provide skills training, and two prisoners eating and living in a cell."

Phil Wheatley, director general of the National Offender Management Service which oversees the prison system, said improvements were being made. "The last six months have seen efforts to control the level of drug availability rewarded, with improved security and search procedures producing a significant drop in positive drug tests."