On board were three crew and nine passengers including two NKVD secret services agents who were guarding a 'large sum' of money. Picture: Russian Searching Movement

The bodies of three men and one woman were found on a remote slope above the Amur River in Khabarovsk region, it was announced. The Italian-made Savoia-Marchetti S.55 flying boat vanished on 26 June 1935 after taking off from Alexandrovsk-Sakhalinksy en route to Khabarovsk.

Lengthy searches at the time failed to find the seaplane or any survivors, although because the incident was promptly classified by the Soviet authorities, full details did not emerge.

The Italian-made Savoia-Marchetti S.55 flying boat vanished on 26 June 1935 after taking off from Alexandrovsk-Sakhalinksy en route to Khabarovsk to be found near Lazarev village. Pictures: The Siberian Times, Russian Searching Movement

On board were three crew and nine passengers including two NKVD secret services agents who were guarding a 'large sum' of money. Two million Soviet roubles at 1935 prices was worth around $2.26 million US dollars.

Members of a search group which found the wreckage after an expedition indicated that there was no money at the site, presumably having been ransacked by treasure hunters who - plainly - had not reported earlier finding the stricken seaplane. For years there have been rumours about the Savoia-Marchetti, including claims the plane was sabotaged.

Members of a search group which found the wreckage after an expedition indicated that there was no money at the site. Pictures: Russian Searching Movement

Wreckage suspected to be from the 1935 crash was spotted by loggers nine years ago, but it has taken until now to organise for the Russia Search Movement to reach the site deep in the taiga in a region the size of the country of Turkey.

The NGO speculated that the pilot had been seeking to follow the river in poor weather when he hit a hillside. 'Probably the pilot noticed too late a steep slope, tried to turn left to gain altitude, but his airspeed was not enough,' said a searcher. The plane crashed around 1 hour 15 minutes into a 5 hour 20 minutes flight.

'Probably the pilot noticed too late a steep slope, tried to turn left to gain altitude, but his airspeed was not enough.' Pictures: Russian Searching Movement

'The passengers were still lying where they fell, thrown out of the wooden cabins of the plane along with the remains of the seating and seat belts. Around them lay their personal items,' said the Russia Search Movement. There were no reports of cash being found at the site.