Child pornography, knuckledusters and sharp knives are among the dozens of items smuggled into Dutch jails and psychiatric prisons last year, the AD said on Friday. The paper bases its claims on internal prison service documents.

The true total is likely to be far higher, given that not every incident is reported, the paper said. In one case, officials failed to report they had found cocaine in a cell, in another, no report was made when a man jailed for firearms offences was found to have bullets, the AD said.

Justice ministry spokesman Jaap Oosterveer told the paper the bullets themselves were handed over to police and it was up to them to decide whether or not to press charges.

‘Prison officials themselves always take measures,’ he said.

The contraband is found in cells during searches, by drugs dogs and special equipment that can find mobile phones.

In one instant, guards found a prisoner attempted to flush a phone through the toilet. They also found 41 packets of cigarettes and 18 phone cards in his cell. In another case, a man in a psychiatric prison had hidden a sharp knife in his wooden leg and had more weapons in his cell.

Acting junior justice minister Klaas Dijkhoff plans to make it a criminal offence subject to a six-month jail term if prisoners are found with contraband. However, it is unclear if there is enough support for the legislation in parliament, the AD said.

Lawyer Sebas Diekstra, who had requested the ministry documents, said prison checks leave a lot to be desired. ‘There is under-staffing and that means checks are not optimal. Most contraband is never found,’ he said.