The Russian air force halted flights of Mi-8 transport helicopters today after a crash landing near the far eastern city of Khabarovsk injured three pilots.
Hours later, four people died when another Mi-8 helicopter used as a civilian craft crashed near the Siberian oil centre of Nefteyugansk, the emergency situations ministry said.
The military Mi-8 helicopter ran into trouble at a height of 3,940 feet when its tail propeller malfunctioned.
Eight parachutists bailed out and the chief pilot crash landed the helicopter, air force spokesman Alexander Drobyshevsky was quoted as saying by the Interfax news agency.