Amsterdam council plans to crack down on landlords who are charging too much rent while using unlawful temporary rental contracts, after revelations about the practice in January.

Since the introduction of an affordable homes law last year, new tenants must be offered indefinite contracts as a rule of thumb.

However the Woon foundation – publicly funded to offer tenants legal help – has raised the alarm about apartments being advertised online for periods such as “a maximum of 72 months”, apparently breaching the law.

Now Zita Pels, Amsterdam head of housing, has said in a briefing to the council that while it does not have legal powers to alter illegal contract terms, it will enforce on rents.

“The council will, wherever legally possible, take action against landlords who wrongly label a lease short term by nature, in order to charge too high a rent,” she wrote. “In this way, it can break apart bogus constructions in terms of the level of rent.”

Amsterdam is lobbying the national government about “fake constructions” that do not qualify for the few exemptions, as well as providing more public information and a boosted enforcement team.

Juliet Broersen, head of the local Volt party, who requested a response from the executive, told Dutch News she was asking for worried Amsterdammers. “We have had a lot of concerned people on the phone,” she said. “The international community [should also] be warned. Some landlords are looking for a way around wherever they can.”

Dutch property prices reached their highest ever average in November last year and the Netherlands is an estimated 370,000 homes short. In a survey of young people between 18 and 29, the Kids Rights charity found more than half are looking for a house and, of these, nine in 10 are having problems.

The affordable homes law, which came into force last July, should cover 90% of rentals. Each property gets a point score based on size and quality: everything up to 143 points can only be rented for up to €900, excluding service costs.

For new contracts with properties from 144 to 186 points, the maximum rent is €1185 a month. Homes with more points can continue to charge market rates. Municipalities have powers to fine misbehaving landlords anything from €21,750 to €87,000.

“Framed”

Landlords have been deeply critical of the law, with many complaining about being framed as criminals. The Raad van State warned it could decrease the supply of rental housing.

However, although private landlords have been selling small apartments, there was no reduction in the total supply of rental property in November, due to new build and professional landlord acquisitions.

A rent tribunal in November slashed the rent for tiny rooms in Amsterdam and another case is ongoing on short stay apartments. But some, like Broersen, believe internationals may meanwhile be targeted if they are unaware of their rights.

Inge van Vierssen-Berghorst, a financial advisor, posted last week on LinkedIn: “Just rent to expats: you only need one. With thanks to the insignificant [affordable rent law].”