'Alright, Good Night' - these turned out to be the final few words heard from the missing Malaysia Airlines flight MH370.

The Malaysian aviation authorities revealed the final conversation between the ground officials and the pilot as they briefed the relatives of the Chinese nationals who were onboard the missing passenger jet.

The briefing in Beijing, led by Malaysian envoy to China Iskandar Sarudin, was attended by nearly 400 people, mostly relatives of the missing passengers.

Almost two thirds of the 227 people onboard the vanished Boeing 777 were Chinese.

The last words from MH370 were in response to Malaysia's air traffic controllers who told the cockpit that the aircraft had entered Vietnamese airspace. The ground officials had told flight 370's pilots that the controllers at Vietnam's Ho Chi Minh City would swiftly take over.

There were no distress calls from the flight before it abruptly disappeared and the reasons behind its vanishing remain unknown. This has triggered widespread speculation and conspiracy theories including those related to sabotage or pilot suicide.

Even if hijackers had taken over and turned off the transponder signals, the pilots could have sent secret emergency Mayday codes, a Malaysian aviation official has said, the New Strait Times reported.

At the briefing, some of the relatives of the passengers accused the Malaysian authorities of covering up an alleged plane hijack, citing the ringing mobile phones of some passengers.

The relatives, demanding more transparent information, accused the officials of negotiating with terrorists who hijacked the plane. They said the fact that any debris of the plane was not found pointed to a hijack.

The meeting lasted for nearly two hours with some pressing the Malaysian envoy for an apology for the government's failure to provide quick and transparent response.

The Kuala Lumpur-Beijing flight, with 239 people aboard, remains elusive more than 90 hours after losing contact and no clues have so far been found to trace the jetliner or its debris.