Police said a suspect is under investigation for violating secure airspace of Drottningholm Palace, the private residence of Sweden's royal family outside Stockholm. File Photo by Mauritz Antin/EPA-EFE
Jan. 31 (UPI) -- One person has been arrested in connection with a series of mysterious drone flights spotted in recent days over Sweden's Royal Palace near Stockholm, authorities say.
Swedish police announced the person was arrested Saturday by security guards at Drottningholm Castle, the private residence of Sweden's royal family, according to national broadcaster Sveriges Radio.
Police spokesman Daniel Wikdahl said the suspect is under investigation for unauthorized access to protected spaces -- the Swedish royal castle is off-limits to such activities.
The suspect is a Russian man in his 40s whose friends claim he is a regular tourist who was unaware of the restrictions against flying drones in the area, the Swedish newspaper Aftonbladet reported.
"He is an ordinary tourist," one friend told the newspaper. "I'm sure of that. I know he went to Sweden, but I do not know exactly where he was going."
"I assume he did not know that the castle is a protected object, he must have flown there by mistake," added another.
Reports of unexplained drone flights in Sweden multiplied this month as residents reported seeing the objects at the castle as well as at nuclear power stations, such as the Forsmark nuclear plant.
The Swedish military deployed patrols and helicopters to the station on Jan. 14 after a drone sighting there, officials said. Drones were also spotted near the Oskarshamn, Ringhals and Barsebäck plants around the same time.
The incidents came a day after the Swedish military announced it had begun patrols of the Baltic Sea island of Gotland amid increased tensions between NATO and Russia over Ukraine.