A Russian military drone is likely to have been flown over a nuclear power plant in Germany, insiders have warned, in what would be another example of worrying Kremlin espionage.

A so-called “enemy object” was flown over the decommissioned facility, as well as a natural gas terminal, in the city of Brunsbuttel, in the state of Schleswig-Holstein, in the north of the country, Bild claimed.

Several other drones have also been spotted in the area in recent days, the report added. It cites an internal police report saying: “The no-fly zone was violated several times by flying over the nuclear power plant. An enemy object, believed to be a military drone, was captured.”

The object was thought to be Russian in origin, sources have said, and may have been launched from civilian ships in the North Sea.

Flensburg public prosecutor’s office is investigating a possible sabotage operation.

Unidentified drones have been spotted over German military bases where Ukrainian soldiers are training in recent months.

Speaking in January, Marcus Faber, a member of Germany’s parliament, told Bild that “Drones are regularly spotted over the Klietz military training area, where the Bundeswehr (German military) trains Ukrainians (on Leopard 1 tank).”

Suggesting Russia was behind the incidents, Mr Faber warned Germany had a “huge amount of catching up to do when it comes to drones,” and needed more modern jamming equipment.

Another German politician, Andreas Schwarz, said: “We must not allow Russia to spy on military training areas with drones.

At least 6,000 Ukrainian soldiers had been trained in Germany by the end of August 2023, with the goal of 10,000 by the end of the year.

Programs have involved general combat training, and the use of advanced equipment like Patriot air defence systems and US-supplied Abrams tanks.