Croatian police have said there is no need for alarm after residents in Zagreb reported UFO sightings as well as seeing strange lights accompanied by a blast on Wednesday morning.

Zagreb Police Department said it has no information of possible flights or explosion sounds but said it is probing the claims. It urged people there is no need for panic.

The reports were made by local Radio Antena, who on their morning show featured Kresimir Misak, the editor of the local science fiction television show "On the Brink of Science."

He claimed that he had seen this unusual occurrence.

Local Index.hr news portal reports that the alleged UFO sighting might be a hoax to cause panic in the Croatian capital.

Should the police determine the reports as false and disturbing, it "will file charges," Krunoslav Borovec from the Zagreb Police Department told Index.hr.