Two unlicensed taxi drivers who work for the online service Uberpop have complained to police after they were harassed by a group of men in cars, the Telegraaf reports on Tuesday.

Uberpop said a small group of drivers are behind the harassment. ‘They are trying to stop changes in the taxi sector with violence,’ a spokesman said.

A police spokesman told news agency ANP two complaints had been made and in one case two men had been arrested for threatening behaviour and reckless driving.

Last month the taxi service association KNV Taxi and Amsterdam taxi firm TCA made a formal complaint against Uberpop, which allows private car owners to offer cheap taxi services in the big Dutch cities.

They want the government to tackle the illegal service as soon as possible. ‘This has been going on for seven months and nothing has changed,’ the organisations said at the time. ‘Despite the fines, illegal Uberpop drivers are still operating.’

In December, the courts ruled Uberpop was operating illegally in the Netherlands but the company has refused to withdraw, despite a maximum fine of €100,000.