(Reuters) - Residents of a building owned by the Kushner Cos on Tuesday sued the real estate company belonging to the family of President Donald Trump’s son-in-law Jared Kushner, alleging the it overcharged them for rent in violation of New York law.

Nine current and former residents of 89 Hicks Street, a residential building in Brooklyn the Kushner Cos purchased in 2014, sued the real estate firm in New York state court. They said the company flouted its obligation under New York law to offer them rent-stabilized leases.

The plaintiffs want their lawsuit to proceed as a class action, saying more than 100 current and former residents of the building could have similar claims.

A spokesman for the Kushner Cos said the company is reviewing the lawsuit and offered no further comment.

New York City has some of the nation’s most expensive housing, but state law requires privately owned buildings built before 1974 with six apartments or more to charge stabilized rents based on formulas set by the city and the state.

The Kushner Cos purchased 89 Hicks Street from Brooklyn Law School in 2014. The school and the building’s previous owner, a religious organization, were exempt from the rent stabilization rules.

The lawsuit contends that the exemption ended when the Kushner Cos purchased the building and that the company should have offered tenants rent-stabilized leases.

The lawsuit is based on an investigation of the building by Housing Rights Initiative, a tenant-rights advocacy group. The organization’s founder, Aaron Carr, said the Kushner Cos rented units for about $2,500 per month but tenants should have been charged substantially less than that.

Lucas Ferrara, a lawyer for the plaintiffs, said the building’s rent-stabilized status was easy to ascertain through due diligence. “It is our contention that this private owner either intentionally or indifferently failed to follow the regulations of the rent law,” he said.

Kushner, who is married to Trump’s daughter Ivanka and serves as a senior White House advisor, stepped down as chief executive officer of the real estate company in January.

Founded by Kushner’s father Charles in 1985, the New York-based company owns 20,000 apartments around the country, mainly in New York and New Jersey.