Malaysia said Monday its missing airliner had crashed in the Indian Ocean, extinguishing the hopes of relatives of those on board but shedding no light on why it veered so far off course.

A sombre Prime Minister Najib Razak said a new analysis of satellite data on Malaysia Airlines flight MH370's path placed its last position in remote waters off Australia's west coast, "far from any possible landing sites."

"It is therefore with deep sadness and regret that I must inform you that, according to this new data, flight MH370 ended in the southern Indian Ocean," Najib said.

The plane went missing on March 8 with 239 people aboard -- two thirds of them Chinese -- en route from Kuala Lumpur to Beijing.

A text message sent to relatives ahead of Najib's announcement said that "we have to assume beyond any reasonable doubt that MH370 has been lost and that none of those on board survived".

The announcement touched off deep despair among relatives in both cities.

"What can I say? I had the belief that my son would return home safely. But what can be done?" said Subramaniam Gurusamy, whose 34-year-old son was on board.

"This is fate. We must accept it," he said, his voice choking with emotion.

In Beijing, family members who have gathered in a hotel during the agonising 17-day wait for information were crushed by the announcement.

Some began sobbing uncontrollably, held by fellow family members, while others collapsed and were taken away on stretchers.

"For them, the past few weeks have been heartbreaking; I know this news must be harder still," Najib said in Kuala Lumpur.

The premier said Monday's conclusions were reached based on new analysis of satellite data by Britain's Air Accidents Investigation Branch (AAIB), and the satellite telecommunications firm Inmarsat.

He gave no specifics such as precisely where the plane may have been lost.

A group of about 30 Chinese relatives later vented their anger to reporters in Beijing, decrying Malaysian authorities as "murderers".

"The Malaysian government, Malaysia Airlines and the Malaysian armed forces are the real murderers who have killed our loved ones," a man said, appearing to read from a prepared statement on a laptop on behalf of the group.

- Multiple debris sightings -

Numerous recent sightings of suspected debris, by satellites as well as aircraft criss-crossing the region, had fuelled the belief that the plane crashed in the southern Indian Ocean.

But the confirmation brought Malaysian authorities no closer to determining what actually caused the Boeing 777 to deviate inexplicably off course and fly for hours and thousands of kilometres (miles) in the wrong direction.

Confirmed wreckage -- to say nothing of the black box and its flight data -- are yet to be found.

"Terrorism, pilot suicide and a complex set of mechanical failures never seen before are now the likely possibilities. A simple failure such as a simple fire or structural failure is becoming very unlikely," said aviation consultant Gerry Soejatman.

The airline said the international search in a stormy stretch of the Indian Ocean would continue "as we seek answers to the questions which remain".

"When Malaysia Airlines receives approval from the investigating authorities, arrangements will be made to bring the families to the recovery area," it said, without specifying where that would be.

With specific information still scarce, China's deputy foreign minister demanded that Malaysia hand over the satellite data that led it to the judgement that the plane was lost at sea.

"We demand the Malaysian side to state the detailed evidence that leads them to this judgement," Xie Hangsheng asked Malaysia's Ambassador to China, Iskandar Bin Sarudin in a meeting late Monday, according to a statement on the foreign ministry's website.

- Competing theories -

Malaysia believes the plane was deliberately diverted by someone on board. But the absence of firm evidence has fuelled intense speculation, competing theories, and tormented the families of the missing.

Leading scenarios include a hijacking, pilot sabotage or a sudden mid-air crisis that incapacitated the flight crew and left the plane to fly on auto-pilot until it ran out of fuel.

The last known contact with MH370 was made over the South China Sea between Malaysia and Vietnam. For reasons unknown, it backtracked over the Malaysian peninsula.

The search swung deep into the Indian Ocean last week after initial satellite images depicted large floating objects there, and a flurry of debris sightings continued into Monday.

- Hunt for 'black box' -

The US Navy on Monday sent a specialised device to the region to help find the "black box" of flight and cockpit voice data, along with a robotic underwater vehicle that can scan the ocean's depths.

The high-tech black box locator can track down flight recorders as deep as 20,000 feet (6,060 metres), the US Seventh Fleet said in a statement. The search area ranges from 3,000-4,000 metres deep.

The 30-day signal from the black box is due to fail in less than two weeks.

Australia said the search for debris grew to 10 aircraft on Monday, with two Chinese military aircraft joining Australian, US, and Japanese planes. Chinese, British and Australian naval vessels are also involved.

As part of an investigation into the crash, Malaysian Transport Minister Hishammuddin Hussein said police have interviewed more than 100 people, including families of both the pilot and co-pilot.

Timeline: the hunt for flight MH370
Kuala Lumpur (AFP) March 24, 2014 - Malaysia announced Monday that a Malaysia Airlines plane which went missing more than two weeks ago crashed in the Indian Ocean, bringing a measure of closure to relatives of the 239 people on board.

Here is a timeline of major developments in the hunt for flight MH370:

SATURDAY MARCH 8

-- The Boeing 777 takes off from Kuala Lumpur at 12:41 am, bound for Beijing. It vanishes from Malaysian civilian radar at 1:30 am, just before passing to Vietnamese air traffic control. It blips on military radars until 2:15 am, but that sighting is only later identified as flight MH370.

-- Vietnam launches a search operation that expands in the following days into a multinational hunt in the South China Sea.

-- Vietnamese planes spot two large oil slicks near the plane's last known location, but they turn out to be a false alarm.

-- It emerges that two passengers were travelling on stolen EU passports, fuelling speculation of a terrorist attack. The two Iranian men are later revealed as suspected illegal immigrants.

SUNDAY MARCH 9

-- Malaysia's air force chief says the plane may have turned back towards Kuala Lumpur for no apparent reason, citing radar data.

-- A Vietnamese plane spots possible debris off southwest Vietnam -- another false alarm.

MONDAY MARCH 10

-- Malaysia sends ships to investigate a sighting of a possible life raft, but only flotsam is found.

TUESDAY MARCH 11

-- The search area now includes land on the Malaysian peninsula, the waters off its west coast, and an area to the north of Indonesia's Sumatra island -- all far from the flight's scheduled route.

WEDNESDAY MARCH 12

-- Malaysia expands the search zone again to include the Malacca Strait off its west coast and the Andaman Sea north of Indonesia.

-- Malaysia's air force chief says an unidentified object was detected on military radar north of the Malacca Strait early Saturday, but says it is still being investigated.

THURSDAY MARCH 13

-- Chinese satellite images of suspected debris in the South China Sea are found to be yet another false lead.

FRIDAY MARCH 14

-- The hunt spreads to the Indian Ocean after the White House cites "new information" that the jet may have flown on after losing contact.

SATURDAY MARCH 15

-- At a dramatic news conference, Malaysian Prime Minister Najib Razak announces that the plane appears to have been flown deliberately for hours, veering sharply off-route at roughly the same time that its communications system and transponder were manually switched off.

-- Satellite data now places the jet anywhere in one of two huge corridors of land and sea -- a northern one stretching into Central Asia and a southern one swooping deep into the Indian Ocean. The search in the South China Sea is called off.

SUNDAY MARCH 16

-- As the number of countries involved in the search jumps to 26, experts examine a flight simulator installed in the home of Captain Zaharie Ahmad Shah.

MONDAY MARCH 17

-- After conflicting statements, officials confirm that the relaxed-sounding last words from the cockpit -- "All right, good night" -- came two minutes before the plane's transponder was shut down.

-- Malaysia Airlines says the voice is believed to be that of co-pilot Fariq Abdul Hamid. Police probe a potential political motive on the part of Captain Zaharie, a supporter and distant relative of Malaysian opposition leader Anwar Ibrahim.

TUESDAY MARCH 18

-- Australian and US surveillance planes begin combing 600,000 square kilometres (230,000 square miles) of the remote Indian Ocean in the southern search corridor.

-- Desperate relatives of the Chinese passengers threaten to go on hunger strike.

WEDNESDAY MARCH 19

-- Malaysia says background checks on almost all passengers and crew have produced no "information of significance".

-- Angry Chinese relatives try to gatecrash Malaysia's daily media briefing on the investigation, unfurling a banner reading: "Give us back our families."

-- With the 26-country search apparently bogged down in coordination problems, Thailand's air force reveals its military radar had picked up what appeared to be flight MH370 just minutes after it was diverted.

THURSDAY MARCH 20

-- Australia says satellites have spotted two objects, one estimated at 24 metres (79 feet) long, in a remote area of the southern Indian Ocean.

-- Four surveillance aircraft are dispatched to the area, as is a Norwegian merchant ship. But in poor weather, they spot nothing.

FRIDAY MARCH 21

-- Planes spend a second fruitless day searching the remote stretch of the Indian Ocean.

-- Malaysia asks the United States to provide undersea surveillance technology.

SATURDAY MARCH 22

-- China releases a new satellite photo of an object floating 120 kilometres (75 miles) from those pictured in the Australian images.

SUNDAY MARCH 23

-- Along with French satellite data indicating floating objects in the area, sightings of a wooden pallet and other debris raise hopes of a breakthrough.

MONDAY MARCH 24

-- China and Australia both announce fresh, separate sightings of objects in the sea, adding to the mounting evidence of debris in the Indian Ocean.

-- The US Navy orders a specialised black box locator sent to the area.

-- Late in the evening, Malaysian Prime Minister Najib Razak announces "with deep sadness and regret" that MH370 crashed into the Indian Ocean, citing new analysis of satellite data. In a message to families, the airline states "we have to assume" the plane was lost at sea.

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