The prisoner, being held at the Skogome prison near Gothenburg, was on a short period of leave in the town of Kungsbacka, where he was accompanied by two warders. Ninety minutes before he was due to go back to the jail, a specialist facility for sex offenders, the warders suggested taking a trip to a sex shop in the town.

The prisoner claims the nature of the shop only became apparent when they got inside, but once there, the warders stayed for “quite a long time,” according to a letter sent by the inmate to newspaper Göteborgs-Tidningen.

The shop in question sells goods such as dildos and inflatable sex dolls. All three men bought products there – the prisoner claimed he did so in order to prove to the authorities that he had been to the shop.

“I can’t understand how staff at a jail for sex offenders can trick a prisoner to go into a shop like that,” the man told Aftonbladet.

Lisbeth Malmqvist, action regional manager for the Swedish prison and probation service, said the visit was “unfortunate” and “goes against everything we teach in our treatment programmes.”

Questioned by prison bosses about the report, the guards said they believed the store was more akin to a joke shop, rather than a sex shop. Lisbeth Malmqvist said the prison service had accepted that the visit was an unfortunate error.