The revelation that flight MH370 ended in the southern Indian Ocean is based on new analysis by UK investigators and the British satellite firm Inmarsat, Malaysia's prime minister has said.
Najib Razak said relatives of the flight's 239 passengers and crew had been told of the "heartbreaking" news.
Inmarsat used new techniques to detect the plane's course, he said.
The UK's Air Accidents Investigation Branch, which probes serious civil aircraft incidents, was also involved.
Malaysia Airlines flight MH370 went missing after taking off from Kuala Lumpur on 8 March.
Mr Razak's announcement came as the international search effort reached a fifth day of operations in the southern Indian Ocean......
BBC News - UK firm behind Malaysia Airlines flight MH370 breakthrough