A group of private landlords are threatening to sue housing minister Kasja Ollongren if she presses ahead with plans to change the way rents are calculated, the Financieele Dagblad said on Wednesday.

They are argueing the changes will mean some properties are again classified as rent controlled, and that would conflict with their rights as owners, the paper said.

Housing rents in the Netherlands are currently determined by a complicated system of points – with extra points allocated for more luxurious fittings and outside space, for example.

Apartments and houses with fewer than 142 points are classed as social housing. The rent may not rise above a maximum (currently €752) and only low income households, usually from a long waiting list, can live in them.

In 2015, the then-housing minister Stef Blok changed the point system to include 100% of official value of the property – a move which pushed thousands of social housing units into the liberalised sector, particularly in Amsterdam and Utrecht.

Ollongren is now planning to partly reverse that change, which could mean up to 28% of properties which are now now rent controlled reverting to the social housing sector.

‘This is a general rule which will impact a small group of investors,’ Anthonie Mans of the Stichting Fair Huur told the FD. ‘Once again we are having to fight against the ridiculous idea that all landlords are exploiting their tenants.’

The government is under considerable pressure to boost the supply of social housing in the Netherlands because of the long waiting lists. Ollongren has already consulted lawyers about her proposed changes and they say that the change is legal, the FD said.