Copenhagen police said the incident began Jan. 17 when an officer in an unmarked car began chasing another officer in an unmarked car because he believed the other officer to be a speeding civilian, The Copenhagen Post reported Monday.
"He takes off after him thinking that he is a criminal and the man in the front car thinks that the man chasing him out of harassment. They are both in civilian clothes, driving unmarked cars, and neither can see it is a fellow officer," Torben Koch, a lawyer for one of the officers, told the Ekstra Bladet newspaper.
The chase ended when the chasing officer rammed the other car, causing the cars to strike a third vehicle.
No injuries were reported.
The officers are now due in court Sept. 25 on charges of seriously endangering traffic safety. Prosecutors said they drove over the speed limit, ignored traffic lights and drove in bicycle lanes without police lights or sirens.
Koch said prosecutors initially decided not to press charges, but later reversed the decision.
"It is deeply reprehensible, because my client's superiors confirmed he had been on duty in an unmarked car," Koch said. "I believe that the original decision was the right decision."