Russian police have been baffled by the sudden disappearance of a small plane in the Urals, the Moscow Times reports.

The plane, a small single-engine An-2 biplane, had taken off without permission from air traffic controllers last night. While the pilot and a security guard are believed to be board on-board, both the co-pilot and flight engineer arrived to find the airplane missing and three abandoned cars.

So far no crash sites have been found, and the crew on board are not responding to phone calls.

In a typically Russian twist, police suspect that the 12 or so passengers who had been planning a journey had been consuming alcohol, and may have taken the plane for an impromptu trip.

"One theory that the police are working with is that the group of people might have gone on a fishing trip," Valery Gorelykh, a spokesman for the regional police told Interfax. "Another version is that they went to a banya in a neighboring district."