JAKARTA (REUTERS, AFP, WASHINGTON POST) - A search and rescue team has found part of the body of a crashed Lion Air plane, Indonesia's military chief said on Wednesday (Oct 31), two days after it crashed into the sea with 189 people on board.

"We strongly believe that we have found a part of the fuselage of JT610," Mr Hadi Tjahjanto told reporters, referring to the flight operated by the Indonesian budget carrier.

Using sonar technology, Mr Hadi said the authorities were confident they had pinpointed the location of the Boeing 737 Max plane that plunged into the sea on Monday.

Mr Haryo Satmiko, the deputy chief of the national transport safety panel, told Reuters: "Yesterday afternoon, the team had heard a ping sound in a location at 35m depth."

"This morning, at 5am, the team has gone back to dive at the location."

The authorities have been searching for the downed jet's location and the plane's black boxes in water some 30m to 40m deep, in the hopes of also finding flight data recorders expected to be crucial to the crash investigation.

The search team had the location coordinates but now had to confirm it was the fuselage, Mr Haryo added.

The plane is believed to have broken up into pieces upon severe impact with the sea surface after it dived at a rapid speed from a height of around 900m.

Officials have said the discovery of body parts suggested a high-impact crash in water off the coast of Indonesia's Java island.

Some 49 body bags filled with limbs and other remains have so far been recovered, the authorities said on Wednesday.

"None of what we have received is in the form of a full body," said Brigadier-General Arthur Tampi, head of the National Police Medical and Health Centre in Jakarta.

"So, it is better if a family member does not open (the body bags) because it can cause trauma."

He cautioned that not all the victims will be found. A police officer added that the body parts are "scattered" all over, complicating the DNA identification process.

While aviation experts have said it is too early to determine what caused the accident, Indonesian National Search and Rescue Agency (Basarnas) operational director Bambang Suryo Aji on Monday ruled out the possibility that the plane exploded in mid-air, as the debris and human remains found showed no signs of being burnt.

The latest developments came as Boeing officials are to meet with Lion Air on Wednesday, after Indonesia ordered an inspection of the US plane maker's 737 Max jets.

The Boeing 737 Max 8, which went into service just a few months ago, crashed into the Java Sea off Indonesia's northern coast moments after it had asked to return to Jakarta on Monday.

Lion's admission that the plane had an unspecified technical issue on a previous flight - as well as the plane's abrupt nose dive just 13 minutes after take-off - have raised questions about whether the plane had any faults specific to the newly released model.

"When you have a new plane, you expect the thing to work exactly like it's supposed to in the written contract... It's in everyone's interest for this thing to work," Dr Stephen Wright, aviation expert at the University of Leeds, told AFP.

Indonesia's transport minister ordered an inspection of all 737 Max aircraft on Tuesday, while representatives from Boeing are due to meet the budget carrier, said Lion spokesman Ramaditya Handoko.

Lion Air group managing director Daniel Putut said the airline had "many questions" for the Chicago-based company and they would discuss the delivery of remaining aircraft 737 Max models, Indonesian news website tirto.id reported.

Lion Air, Indonesia's biggest budget airline which has been engaged in huge expansion, announced earlier this year it was buying 50 Boeing 737 Max 10 jets for US$6.24 billion (S$8.65 billion). Boeing suspended release of the fuel-efficient 737 Max just days before its first commercial delivery last year due to an issue with engines.

But the narrow-body jet was subsequently cleared for commercial delivery and has had thousands of orders from more than 100 customers worldwide.

Boeing said in a statement that it was providing technical assistance at the request and under the direction of the Indonesian authorities, but did not comment on the reported meeting.

A team of US government and Boeing investigators are to arrive in Indonesia on Wednesday evening to help with the investigation of the downed plane.