Prime Minister Lee Hsien Loong said on Monday he was deeply saddened by news that Malaysia Airlines flight MH370 has crashed.

"For more than two weeks, we have been hoping against hope that somehow the worst did not happen. We know how anguished and desperate the families and friends of those on board felt," he wrote in a Facebook post.

"While we are still far from understanding what happened, I hope this latest news will nonetheless give some certainty and closure," he added.

"My deepest sympathies and condolences to the families and friends of those on board, and to the governments of Malaysia and China."

Acting Minister for Culture, Community and Youth Lawence Wong, in a Facebook post, also expressed his deepest sympathies and prayers to the families and friends of those on the flight.

Malaysian Prime Minister Najib Razak announced on Monday night that the plane, which disappeared on March 8 while travelling from Kuala Lumpur to Beijing with 239 people on board, was assumed to have crashed in the southern Indian Ocean with no survivors. He cited new analysis of satellite data which indicated MH370 flew along the southern corridor, and that its last position was in the middle of the Indian Ocean, west of Perth. "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," he said at a hastily arranged media briefing.