A Swedish prosecutor Tuesday launched a preliminary investigation to determine if Foreign Minister Margot Wallstrom's receiving a rented flat from a trade union constituted bribery.
Alf Johansson of the National Anti-Corruption Unit said it remained to be determined if a crime had been committed and there were no suspects so far.
Last week, the Aftonbladet daily disclosed that Wallstrom had secured a lease for a flat in central Stockholm owned by the Swedish Municipal Workers' Union, which owns several apartment buildings.
The disclosure triggered headlines due to Wallstrom's cabinet position and the difficulty in acquiring a lease in the Swedish capital. Questions were also raised whether Wallstrom risked undue influence by the union.
Johansson told Swedish Radio news that he acted both on complaints filed by members of the public and reports in the media, referring to Aftonbladet's report.
Political commentators said the disclosure also reflected how "dysfunctional" Stockholm’s rental housing market is.
The average waiting time for a rental flat in central Stockholm is 15 years via the municipal housing queue, where over 500,000 people were registered at the end of 2015.
Wallstrom welcomed the prosecutor's investigation, adding she had "nothing to hide. I will continue to do my job," she said in a statement.
Before signing the lease in April 2015, Wallstrom said she had been assured she was not jumping ahead of anyone in the union's internal queue.
The Municipal Workers' Union said it supported a probe, too.
Traditionally, the trade union movement and Wallstrom's Social Democrats have close ties. Prime Minister Stefan Lofven, for instance, is a former head of the Metal Workers' Union.
Lofven said in a statement that it "was good this matter will be clarified."
The leadership of the Municipal Workers' Union has been under fire since Aftonbladet last week began publishing a series of articles alleging widespread mismanagement. The union was reported to own a loss-making restaurant and conference centre, while union leaders are alleged to have paid for weekend trips and alcohol with membership fees.
Following last week's resignation of the union treasurer, union chairwoman Annelie Nordstrom has rejected calls to step down, saying she wanted to "fix matters" before a union congress in May.
Meanwhile, members of two opposition parties have asked parliament's constitutional affairs committee to review Wallstrom's flat arrangement.