Malaysia Airlines flight MH370 crashed into a remote area of the southern Indian Ocean, killing all 239 people on board, Malaysia’s Prime Minister Najib Razak has announced.

While debris potentially linked to MH370 was spotted by planes off Australia on Monday, Mr Najib's announcement instead came off the back of new satellite data that confirmed the flight's path south.

“This is a remote location, far from any possible landing sites,” Mr Najib told a media briefing.

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

Relatives of the pilots and crew were told of the news late on Monday night, ending an agonising wait to learn the fate of their loved ones.

Many of them had refused to believe those on board had perished.

Confirmation the Boeing 777, one of the world’s most sophisticated airliners, crashed into the sea came from Britain’s Air Accidents Investigation Branch which had been provided information from the London-based satellite company Inmarsat.

According to the analysis the plane flew for more than seven hours after it had turned back from its scheduled flight path over the South China Sea.

Officials said it was likely the plane ran out of fuel before crashing.

It is not known whether the pilots were still in control of the plane during the long flight into the Indian Ocean.

Perth will now become the base for a multi-nation recovery effort.

Debris spotted off coast

On Monday, 18,500 square nautical miles were searched in the Australian search area.

Two orange objects approximately one metre in length and one white coloured drum were sighted by search aircraft, but remain unidentified and have not been conclusively linked to MH370.

The Australian warship HMAS Success spent the night in an area where the military aircraft P-3 Orion on Monday spotted the objects bobbing in rough seas that appeared to be debris from the plane.

Prime Minister Tony Abbott telephoned Mr Najib late on Monday to tell him about the objects, however nothing concrete was found before the search was suspended on Monday night.

HMAS Success detected two radar targets within the search area, but could not locate the targets on further investigation.

Hopes were high the debris could be recovered on Tuesday morning.

Twenty-six countries have been involved in the largest search for an aircraft on record in an area of 2.4 million nautical miles.

More than 20 ships and planes from countries including Australia, China, Japan, India and the United States are now expected to step-up their search.

The breakthrough

Inmarsat used a type of analysis, never used before in an investigation of this sort, to determine that the plane flew off course.

Mr Najib said the company concluded the plane flew along a southern corridor into the vast expanses of the Indian Ocean after inexplicably turning back from its scheduled flight path from Kuala Lumpur to Beijing on March 8.

The Inmarsat analysis will allow search coordinators to narrow what had been a large search area.

They will also be able to calculate how far the plane could have approximately flown with the fuel it had on board.

Malaysian authorities say finding the plane’s black box recorder will be crucial in discovering how the plane lost communication and turned back from its flight path.

Passenger grief turns to anger

A text messsage was sent by Malaysia Airlines to the families of passengers of Flight MH370 on Monday night.

It read: "Malaysia Airlines deeply regrets that we have to assume beyond any reasonable doubt that MH370 has been lost and that none of those on board survived.  As you will hear in the next hour from Malaysia’s Prime Minister, we must now accept all evidence suggests the plane went down in the Southern Indian Ocean."

In Beijing, mixed with the grief among the relatives at the Lido Hotel was a sense of rising anger and disbelief.

Families had long been upset at what they perceived to be a gross mishandling of the investigation. Many were, and appear to remain, convinced that the Malaysian government has been complicit in an elaborate cover-up - a conspiracy theory that has enabled them to avoid the more plausible reality.

"The Malaysian government is too dark," one woman wailed.

"Why won't you tell the truth, why don't you respect our families?"

After more than a fortnight of holding on, the abrupt nature and brevity of the Malaysian announcement has proven hard to accept.

"I've been waiting half a month and they just give us one sentence?" one woman yelled to reporters.

Most though, have been too debilitated by grief to get angry. One woman, sat slumped on the ground, as her concerned companion called out for help.

As paramedics crouched down, her the companion explained that her son was on the plane.

"I don't want to get up," the woman said. "I don't want to go home. I don't want to go anywhere."

Mystery still not solved

Malaysian authorities said more than a week ago there was evidence of a “deliberate action” by someone on board.

But after investigations into all those on board, including the pilots, failed to uncover any links to extremist groups or anything suspicious, investigations have turned to the possibility of an explosion, fire or mechanical failure.

Investigators are now looking at whether the pilots became unconscious after turning the plane around.

After interviewing more than 100 people, including the families of the pilot and co-pilot, police admit they have no strong leads in one of the most baffling mysteries in modern aviation history.

Mr Najib said Malaysia Airlines' officials broke the news to the families of the passengers and crew in Kuala Lumpur and Beijing.

“For them, the past few weeks have been heartbreaking,” he said.

“I know this news must be harder still …I urge the media to respect their privacy and allow them the space they need at this difficult time.”

Mr Najib, whose government has been criticised by China for its handling of the search and investigation, said he called a late night press briefing to release the information “out of a commitment to openness and respect for the families, two principles which have guided this investigation.”

Malaysia Airlines has promised to fly the next of kin and crew to Perth.

More than half of the passengers were Chinese nationals.