KUALA LUMPUR - Malaysia's prime minister has announced that missing flight MH370 crashed in the southern Indian Ocean.
Najib Razak said this was the conclusion of fresh analysis of satellite data tracking the flight.
Malaysia Airlines had told the families of the 239 people on board, he said.
Standing sombre before the world's media, Malaysia's prime minister ended weeks of limbo with a brief statement.
The BBC has seen a text message sent to families by the airline saying it had to be assumed "beyond reasonable doubt" that the plane was lost and there were no survivors.
There were 227 passengers on flight MH370, many of them Chinese.
Relatives of those on board who watched the announcement at a Beijing hotel wept with grief, and some were taken away on stretchers by medical teams.
China has demanded that the Malaysian authorities make available the evidence on which they based their announcement about the jet's fate.
And some relatives of Chinese passengers expressed scepticism about their conclusion, as the plane has not been found yet.
Flight MH370 disappeared after taking off on 8 March from Kuala Lumpur.
A big international search operation has been taking place in the southern Indian Ocean, along the southern arc or corridor of the plane's possible route, more than 1,500 miles (2,500km) off the south-west coast of Australia.
However, the search had to be suspended on Tuesday due to bad weather, the Australian Maritime Safety Authority (Amsa) said.
The unidentified objects have been seen in separate parts of the vast search area, in some of the world's most treacherous and remote waters.
The announcement by Prime Minister Najib Razak came at a late-night news conference in Kuala Lumpur.
It was based on new analysis by British satellite firm Inmarsat, which provided satellite data, and the UK's Air Accidents Investigation Branch (AAIB).
The firms "have concluded that MH370 flew along the southern corridor, and that its last position was in the middle of the Indian Ocean, west of Perth," Mr Najib said.
"This is a remote location, 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."
Mr Najib appealed to the media to respect the privacy of the families of the passengers and crew, saying the wait for information had been heartbreaking and this latest news harder still.