Indonesia rescuers spotted on Thursday wreckage of a Russian Sukhoi aircraft that went missing with up to 50 people on board the previous day in a mountainous area south of the capital while on a demonstration flight.
A search helicopter spotted the wreckage on the edge of a cliff at 5,500 feet, they said. There was no word about the fate of those on board.
"The airplane crashed at the edge of Salak mountain ... An investigation must be done immediately and thoroughly," President Susilo Bambang Yudhoyono told a televised news conference.
Radio contact with the Superjet 100 aircraft, Russia's first all-new passenger jet since the fall of the Soviet Union, was lost at about 4:00 a.m. EDT (0800 GMT) on Wednesday after it descended to 6,000 feet around Mount Salak, a dormant volcano 7,254 feet above sea level, officials said.
Rescuers who began searching the heavily wooded area about 40 miles south of the capital, Jakarta, at first light were converging on the site of the debris, said search and rescue official Ketut Parwa.
The aircraft was carrying Indonesian businessmen, Russian embassy officials and journalists. Dimitry Solodov from the embassy said there were eight Russians on board, including pilots and technicians.
Those on board included eight crew and 42 guests according to figures from the Russian embassy, Sunaryo, chairman of Sukhoi's Indonesian agent, PT Trimarga Rekatama, told a news conference late on Wednesday.
The aircraft made two demonstration flights on Wednesday. It returned to Halim Perdanakusuma airport, east of Jakarta, after the first flight where some people got off and others boarded.
Sukhoi, which has orders for 170 planes worldwide, plans to produce up to 1,000 Superjets, primarily for foreign markets.
It aimed to sell 42 planes to Indonesia, which is seeing a fast-expanding aviation market that aims to tap travel by a growing middle class in the world's fourth-most populous nation.
The jet was developed with Western design advice and technology from companies including Italy's Finmeccanica, as well as avionics and engine equipment from French aerospace firms Thales and Safran.
Built in a converted corner of a Sukhoi fighter factory in Siberia, the Superjet was unveiled in 2007 as part of a drive to restore pride in Russia's aviation industry, but it ran into a series of development delays.
The Superjet 100, with a capacity of 68-103 passengers, is already in service with Russia's Aeroflot and Armenian carrier Armavia and is half way through a 15,500-km (9,630-mile), six-nation Asian tour to try to drum up more international customers.
The aircraft is being marketed internationally in partnership with Finmeccanica subsidiary Alenia Aeronautica.