Hundreds of prison staff have been caught smuggling drugs, weapons and mobile phones into jails, according to the Observer.
A Freedom of Information request by the paper found that 341 staff in England and Wales had been dismissed, excluded, convicted or cautioned by police in the past six years as a result.
Last year, there were 71 cases of staff smuggling – up from 50 in 2015.
The prison service said the figures reflect the actions of a tiny minority.
The response to the Observer’s FoI request showed that it was not just prison officers sneaking in the items, but also health workers, trainers and other support staff.
Drugs were found 13,119 times in prisons in England and Wales last year, the paper said – the equivalent of more than 35 incidents per day and three times the amount as in 2014.
The Prison Officers Association (POA) said the value of the drug market in jail is around £100m.
Ben Crewe, deputy director of Cambridge University’s Prisons Research Centre, told the paper that the lack of staff and a higher number of inexperienced officers meant “those in post are more vulnerable to corruption”.
The POA warned of staff shortages earlier this year, saying it had lost in excess of 7,000 frontline staff since 2010 – despite a recent push to recruit 2,500 officers.
A report by the HM Inspectorate of Prisons in July found that staff shortages at Wandsworth Jail in south London meant visitors were not routinely scanned.
A spokesman for the prison service from the Ministry of Justice said: “The overwhelming majority of our prison staff are hard-working and honest.
“But we remain vigilant to the threat posed by corruption and wrongdoing of a very small number of our staff.”