JAKARTA: Body bags containing the victims of a Russian jet crash arrived in the Indonesian capital Saturday as Russian investigators flew in to probe how the new aircraft smashed into the side of a dormant volcano.

Rescuers said the bodies of those who perished when Sukhoi's new Superjet 100 hit Mount Salak in western Java on Wednesday, killing all on board, were badly dismembered and had been placed in 16 body bags.

"Today we did the evacuation by land and air, and we brought all 16 body bags to Jakarta. Tomorrow, we will continue the search," rescue chief Daryatmo said Saturday evening.

"We are moving around to different places to find more bodies because they were scattered over many spots," rescue chief Daryatmo said, adding that rescuers will attempt to go into a deep ravine Sunday where they believe more remains lie.

Family members waiting at the the Kramat Jati Police Hospital wailed as the body bags arrived by ambulance from the airport and were handed over to forensics.

The bodies will be reconstructed "as much as possible", national police forensics expert Anton Castilani said at the hospital.

The Sukhoi jet disappeared off radars on Wednesday afternoon during what was supposed to be a 40-minute demonstration flight to tout Russia's first post-Soviet civilian aircraft.

Officials confirmed Thursday that there were no survivors on the plane carrying at least 45 people, mostly Indonesian airline representatives and eight Russians.

As the bodies arrived at Jakarta's Halim Perdanakusuma military airport, two Russian jets also landed carrying medics, helicopters and experts who will work with Indonesian authorities in the investigation.

"Forty people from Russia will go to the site to familiarise themselves with the area tomorrow," Daryatmo said, adding they hoped to find an intact part of the plane body to collect.

Questions now swirl over why the plane crashed with an experienced pilot as its captain. The aircraft's black boxes still have not been found at the site, just 80 kilometres (50 miles) south of Jakarta.

A Russian fact-finding committee said Thursday there were indications that safety standards were violated.

Key to the mystery is why the pilot requested permission from air traffic control to descend from 10,000 feet (3,000 metres) to 6,000 feet before the plane disappeared from radar screens and slammed into Mount Salak, which rises to 7,200 feet.

The transport ministry confirmed a control tower in Jakarta gave the pilot permission to descend as the plane approached a military base, where mountains reach around 3,000 feet.

"Based on a report from the control tower, we know the pilot made the request to descend to 6,000 feet, and yes, the control tower gave him permission to do so," the ministry's director general for aviation Herry Bakti stated.

"He was approaching the Atang Senjaya military base, which is a safe place to fly low, and we know that he did in fact descend to 6,000 feet. We think he wanted to show the passengers the military base."

Bakti said it was unclear what happened after that.

Sydney-based aviation expert Tom Ballantyne said that pilots of exhibition flights sometimes "do things you wouldn't normally do" and that they often "like to show off".

"They may be flying over a landmark that is attractive and request to fly lower to give passengers a better view. You may want to show potential customers the way the aircraft can climb or descend at a certain rate," he said.

Sukhoi's representative company in Indonesia, Trimarga Rekatama -- which organised the promotional flight -- said 73 Russian experts, including mechanics, were due to join the investigation.

The company has apologised for confusion surrounding its manifest, claiming at first that 50 passengers were on board but revising the number down to 45. Local rescue officials said the plane was carrying 46.

The company said the final passenger list was with a staff member on the plane, causing confusion as to who exactly was on board.

"We are so sorry about that. It was a mistake. The list should have been with us on the ground," a consultant with the company Sunaryo said.

Photos of the plane's earlier demonstration flight posted online by Russian blogger Sergey Dolya show relaxed passengers smiling on board, being treated to champagne, as well as Russian and Indonesian crew posing outside the jet.

A French and US national were also on board the flight, and police said Indonesia was working with Interpol's disaster victim identification agency based in Lyon, France.

The flight was part of an Asian sales tour to promote the aircraft, a joint venture between Sukhoi and Italy's Alenia Aeronautica, which made its first commercial flight last year. (AFP)