One in three owners of video doorbells registered with the police are keeping recordings for longer than allowed, putting privacy rules at risk, regional broadcaster Omroep Gelderland said on Thursday.

Research agency Multiscope estimates there are about 1.6 million video doorbells in the Netherlands. More than 350,000 are registered with the police system, which allows officers to request footage when investigating burglaries or other crimes. The register includes video doorbells from private individuals and organisations.

Owners who sign up must state where the camera is located, whether it films the street and how long recordings are kept.

Under privacy law, images of the public road may only be stored for “as long as necessary” which in most cases is a 28 day maximum, says law professor Gerrit-Jan Zwenne of Leiden University. The police also use 28 days as the guideline for cameras registered in the system.

However, the register shows that one in three private owners whose cameras film the street keep footage for longer, Omroep Gelderland said.

Police spokesperson Jet Holtus told the broadcaster the register helps investigations because citizens can contribute evidence, but stressed that the police are not responsible for checking how long recordings are kept.  That task, she said, lies with the Dutch data protection authority.

The authority received 550 complaints about doorbell cameras last year but has never issued a fine.

Privacy group Bits of Freedom spokeswoman Lotte Houwing said it is not surprising that many owners keep recordings too long, but warned that the system allows public spaces to be filmed on a large scale.

MP Barbara Kathmann from the GroenLinks-PvdA alliance said she will raise the issue with the minister. Problems with retention periods are common, she said, referring to the telecom company Odido, which kept customer data longer than necessary and was subject to a massive hack.

“In the meantime more and more surveillance devices are appearing in residential areas,” she said. “We need stronger laws that protect people at all times.”