Five people have been placed in solitary confinement at Zaanstad prison after they were found to have drugs and illegal telephones during a major search operation earlier this week.

The Telegraaf newspaper carried photos and videos showing prisoners clearly under the influence of drugs, which were described by justice minister Sander Dekker as ‘completely unacceptable’.

Zaanstad prison was opened two years ago and has cell space for around 1,000 prisoners, making it the biggest in the country.