Romanian traffic police said Monday they were investigating a man who they said illegally drove a car with license plates featuring an obscene anti-government slogan, writes AP.

Police stopped the man early Monday, confiscating the plates and taking away his driving license. The man was taken to a police station and informed police was opening an investigation against him.

The man, who lives in Sweden, told reporters he considered the police action to be “harassment.”

The case gained national attention in recent days, with some Romanian media reporting the car was only authorized to be driven in Sweden.

However, Sweden’s embassy in Romania said the personalized license plates had been issued by the Swedish Transport Agency and were valid for travel in the European Union.

In a statement, traffic police said they were probing whether the 45-year-old Romanian drove an unauthorized vehicle in Romania. That offense carries a maximum penalty of six years in prison.