Finnish police (Illustrative photo: Kimmo Brandt/EPA)

An unknown drone was spotted flying over the Valajaskoski hydroelectric power plant near the Finnish city of Rovaniemi. This was reported by the broadcaster Yle with reference to law enforcement.

The UAV was spotted last weekend. Since August, power plants have become no-fly zones, where drones are prohibited.

A passerby spotted the UAV in Rovaniemi and called the police. Law enforcement agencies in the region confirmed this information, but did not disclose details due to investigative measures.

The media reports that this hydroelectric power plant belongs to Kemijoki Oy. According to the head of the emergency service, Juha Kutolahti, video surveillance is conducted at the power plants, but it did not record the UAV operator.