"The building was damaged but no-one was injured in the incident early on Saturday, which took place just outside the city centre," reported BBC.

This is the second explosion reported from the city this week.

A powerful explosion hit outside the national tax agency on Tuesday.

It is not clear whether the two incidents are linked.

Police say they are looking for a man who was seen fleeing the scene of the police station blast, who was wearing dark clothing and white shoes, reported BBC.

"This was not an accident, but a deliberate act," Chief Police Inspector Jorgen Bergen Skov was quoted as saying by BBC, adding that while the investigation was still under way, nothing suggested it was terror-related.

"These were attacks against buildings, not people," he said. "But it is too early to say anything about the motive."