Malaysian authorities have said that police had searched the homes of a missing airliner's two pilots and were examining the captain's home flight simulator, but warned against "jumping to conclusions".
"Police searched the home of the pilot on Saturday, 15 March," a statement by the transport ministry said, referring to Captain Zaharie Ahmad Shah, 53.
"Officers spoke to family members of the pilot and experts are examining the pilot's flight simulator."
The statement added: "On 15 March, the police also searched the home of the co-pilot."
Fariq Abdul Hamid, 27, was co-pilot of Malaysian Airlines Flight 370, which vanished eight days ago, sparking a massive international search across a huge swathe of Asia.
Malaysian Prime Minister Najib Razak said yesterday the plane appeared to have been deliberately diverted from its flight path after it dropped off radar.
He said satellites continued to detect it for hours afterwards, an announcement which raised fears of a hijack or rogue action by pilots or crew.
The revelation has prompted fresh scrutiny of the two pilots.
Mr Zaharie is said to have assembled his own complex flight simulator at home but nothing has emerged to cast suspicion on him.
The government statement said engineers who may have had contact with Malaysia Airlines Flight 370 before it took off on 8 March were also part of the probe into the missing jet, but called this "normal procedure" for such an event.
"We appeal to the public not to jump to conclusions regarding the police investigation," it said.
It reiterated that all crew and passengers on board the flight were being investigated for possible leads.
Nothing that suggests a motive had yet surfaced, it said.
The plane disappeared from civilian radar less than an hour into its journey from Kuala Lumpur to Beijing.
Mr Najib also said investigators believe that systems relaying MH370's location to air traffic control were manually switched off before the jet veered westward.
An Australian television programme earlier broadcast an interview by a South African woman who alleged that she and a friend were invited into the cockpit of a 2011 flight co-piloted by Mr Fariq, in breach of post-9/11 security rules.
Meanwhile, Malaysia’s police chief has said investigators are still waiting for some countries to send background checks on passengers who were on the missing plane.
"There are still a few countries yet to respond to our requests," Khalid Abu Bakar told a news conference.
Police are also investigating airport ground crew.