Some 25 countries are now involved in a vast search operation for the missing airliner that disappeared over a week ago, Malaysian officials say.
The search area – from central Asia to the southern Indian Ocean – takes in vast tracts of land and sea.
An already complex search operation has become even more difficult, Malaysia’s transport minister says.
Crew, passengers and ground staff are being investigated after it was confirmed the jet was commandeered.
Investigators are trying to obtain the radar data from any of the countries that Malaysia Airlines flight MH370 may have passed over, with its 239 crew and passengers.
Malaysian officials are contacting countries including Kazakhstan, Uzbekistan, Kyrgyzstan, Turkmenistan, Pakistan, Bangladesh, India, China, Myanmar, Laos, Vietnam, Thailand, Indonesia, Australia and France.
They are also asking countries to provide assistance in the search for the plane, including satellite data and analysis, ground-search capabilities, and maritime and air assets.
The police are also reportedly looking at the family life and psychological state of the plane’s pilot, Zaharie Shah, and co-pilot, and searched their homes on Saturday.
Officers spoke to relatives of the pilot and experts are examining the pilot’s flight simulator.
Those who know Mr Zaharie insist he is a normal family man, reports the BBC’s Jonah Fisher in Kuala Lumpur.
Fifty-three years old – with 18,000 hours of flying experience – he is a self-confessed “aviation geek” and proudly posted pictures online of the flight simulator he built at home.
As well as the crew and passengers, police are investigating the engineers who may have had contact with the aircraft before take-off.