Organised crime has flourished in jails where there is a shortage of experienced staff, a former chief inspector of prisons has said.
Professor Nick Hardwick told MPs the absence of long-serving officers had left a “vacuum” which has been filled by inmates involved in the illicit trade in drugs behind bars.
He suggested an “alternative structure” has developed where prisoners had too great an influence in some establishments.
Prof Hardwick said: “I’m quite sure that in some prisons the absence of experienced staff has left a vacuum that organised crime has filled.
“If you want to have a profitable trade in drugs, you need some rules and structures by which that trade operates.
“There’s a lot of money at stake. People need to pay – you can’t go to the small claims court if they’re not.
“What’s certainly happened in some prisons is an alternative structure has developed where prisoners are running too much of what is happening.
“Once established, that becomes very difficult to break down.”
Prof Hardwick did not single out specific prisons, but his remarks to the Commons Justice Committee chime with warnings raised in recent reports published by his successor as chief inspector Peter Clarke.
An assessment of HMP Birmingham warned violent prisoners could act with “near impunity” and blatant use of illegal substances went largely unchallenged amid a “looming lack of control”.
A report on HMP Bedford found inmates had effectively taken control at the violent, overcrowded and vermin-infested jail.
Authorities estimate there are around 6,500 prisoners with links to organised crime in England and Wales.
The Government has announced a string of measures aimed at loosening the grip of gangs and stopping criminal kingpins from continuing their activities from behind bars.
In the latest step, announced earlier this month by Justice Secretary David Gauke, a new specialist unit will identify and freeze bank accounts linked to organised crime.
Prof Hardwick also warned that prisons are struggling to retain staff amid surging levels of violence.
He told the committee: “You get punched. Why would you turn up to work with these levels of violence?
“Secondly … you can earn more money in comparable or less stressful jobs close by.”
He also cited training and staff support as potential factors behind the retention problem.
A Prison Service spokesman said: “We have long been clear that criminal gangs threaten the stability and security of our prisons which is why we are investing £14 million each year to cut off their ability to do business.
“A range of measures have been introduced to identify, disrupt and move ringleaders, while the financial crime unit announced by the Justice Secretary last week will freeze bank accounts linked to organised criminals in prison.
“We are also investing £40 million to fund safety and security improvements, including airport security-style scanners, phone-blocking technology, enhanced perimeter searches and more drugs detection dogs.”