Dutch health insurance companies are investing millions of euros in pharmaceutical companies which charge extremely high prices for their drugs, the Volkskrant reported on Wednesday.

The total investment may only be a fraction of their total invested assets of €15bn, but it does mean there is a conflict of interest with their main function – keeping healthcare costs as low as possible – the paper said.

Last year, for example, CZ invested €1.6m in Biogen, Vertex and Gilead, three firms which have been criticised for their high prices and refusing to justify the cost. Menzis had €1.2m in Biogen while Zilveren Kruis invested in Biogen and Gilead, the paper said.

Biogen, which booked profit of €3.7bn last year, makes a drug to combat the muscle disease SMA, which costs hundreds of thousands of euros a year per patient, the paper said.

VGZ also had investments in the controversial companies but recently sold its shares following criticism from the Dutch healthcare institute.

The institute, which makes recommendations to the government about what the basic health insurance package should include, said last month that insurance companies were acting unethically.

‘You cannot sell this [to the public],’ Utrecht University professor Toine Pieters told the paper. ‘It is painful and perverse. Health insurers are supposed to use their money to make sure medicine is available to all at as low a price as possible.’

A spokesman for Menzis told the paper that having an investment in the company allowed it to exercise pressure on policy. In addition, a healthy return on its investment helped keep premium prices low.