Jakarta - A Russian Sukhoi Superjet 100 with about 50 people on board went missing in a mountainous area south of the Indonesian capital Jakarta during a demonstration flight on Wednesday, officials said.

The plane disappeared from radar screens 50 minutes into what was meant to be a brief flight and rescue teams were headed on foot towards Salak mountain, where the plane went missing.

“We suspect the plane crashed, but we're not yet certain,” rescue chief Marsdya Daryatmo told reporters several hours after the disappearance.

“We tried to send two helicopters to search for the plane... but because of bad weather and strong winds they had to return. We will send them out again tomorrow,” he said.

Two helicopters were forced to turn back on Wednesday night because of bad weather and poor visibility, Daryatmo said.

By midnight, hundreds of rescuers had set up three posts around the mountain.

“We arrived here very late at night, and we plan to set out at dawn. Others are already searching by foot,” Joshua Banjarnahor, a rescuer at a post set up at Cidahu town, told reporters.

“There are hundreds taking part in the search and helicopters will again go out Thursday at sunrise.”

There were scenes of grief at the airport in Jakarta on Wednesday, with relatives of some passengers sitting on luggage carousels weeping uncontrollably, waiting on tenterhooks for information about the missing plane.

Yanny Mariana's eyes welled up with tears as she told reporters that one of her four friends on the flight had called her in a panic.

He had earlier told her the plane would fly above the city of Bandung and be back in Jakarta in under an hour.

“But at around 3pm he called me in a panic and I was worried because I knew it shouldn't take that long to fly to Bandung and back,” she said.

Reports of the exact number on board varied, with local rescue officials saying it was carrying 46 people and Trimarga Rekatama, the company responsible for inviting the passengers, saying 50 were on board.

Herry Bakti, head of the aviation division of Indonesia's transport ministry, said Superjet was on the second of two demonstration flights, and those on board were invited guests.

A list of 36 passenger names posted at Halim airport showed most of them were Indonesian airline and aviation officials, plus five journalists and a representative of French aircraft engine maker SNECMA with a Vietnamese name.

The French embassy in Jakarta confirmed there was one Frenchman aboard.

The Superjet made its first commercial flight last year and if a major accident is confirmed it would be the first disaster to involve the aircraft.

The Superjet 100 is a new passenger aircraft built by legendary Russian planemaker Sukhoi in an attempt to lift the country's civil aviation industry from a post-Soviet crisis.

The plane took off at 2pm from east Jakarta's Halim Perdanakusuma airport, which is used for some commercial and military flights.

“At 2.50pm it dropped from 10 000 feet (around 3 000m) to 6 000 feet,” the rescue agency said in a text message to AFP. Salak mountain, where the plane disappeared, is more than 7 200 feet (2 200m) high.

Russia's RIA Novosti news agency reported 36 non-Russians on board and eight Russians, four of them crew and the others Sukhoi company representatives. It named the captain as Alexander Yablontsev, 57, a veteran pilot.

The Superjet is crucial to Russia's hopes of becoming a major player in the modern aviation market and improving its image in the industry, which has been scarred by frequent crashes of ageing Soviet-era jets.

The project is a joint venture between Sukhoi and Italy's Alenia Aeronautica, part of aerospace and defence giant Finmeccanica.

A mid-range airliner, the Superjet 100 is designed to carry up to 98 passengers and is a direct rival of aircraft by Brazil's Embraer and Canada's Bombardier.

So far it is being flown by two airlines, Russia's Aeroflot and Armenia's Armavia, but orders have been confirmed with more, including Indonesia's Kartika Airlines and Sky Aviation, state-run news agency Antara reported.

The demonstration flight in Indonesia was part of an Asian roadshow that started on May 3 to promote the aircraft. It earlier took in Kazakhstan and Pakistan, and was due to go on to Laos and Vietnam.

A source at the Russian Ministry of Industry and Commerce told the Interfax news agency that the plan was “in perfect condition”.

But Aeroflot has had trouble with its Superjets, with its first one spending several weeks grounded upon delivery because of an air conditioning problem, and in March, a plane had to cut short a flight after encountering problems with its undercarriage.

The sprawling Indonesian archipelago relies heavily on air transport but has a poor aviation safety record. - Sapa-AFP