The helicopter with two crew members and two passengers on board went missing at 11:30 a.m. Moscow time (08:30 GMT) on Monday and rescue services said they had received a report that the aircraft had crashed in the Nefteyugansk district at 3:36 p.m. Moscow time (12:36 GMT).
"Rescuers made it to the crash site at 9:00 p.m. Moscow time (18:00 GMT) and discovered the bodies of four people,'' a spokesman for the local emergencies services said.
Earlier reports said the people on board the Mi-2 helicopter had been injured.
The Mi-2 helicopter, owned by the Russian air company Convers Avia, was making a flight to check facilities owned by Yuganskneftegaz, Rosneft's largest oil-producing enterprise, located in the Khanty-Mansi Autonomous Area.
The latest report comes just after a Mi-8 helicopter crashed in Altai, south Siberia, on Friday, killing seven people, including the Russian president's envoy to the State Duma, Alexander Kosopkin. The helicopter was discovered on Sunday.
