Intensive background checks of everyone aboard a missing Malaysian jetliner have so far failed to find anyone with a known political or criminal motive to crash or hijack the plane, Western security sources and Chinese authorities have said.

Malaysia said it had conferred with the US and Chinese ministers on the search for Malaysian Airlines Flight MH370, an unprecedented 26-nation operation that now spans Asia from the Caspian Sea to the southern Indian Ocean.

Investigators are convinced that someone with deep knowledge of the Boeing 777 and commercial navigation diverted the jet, carrying 12 crew and 227 mainly Chinese passengers, perhaps thousands of miles off course.

China's ambassador to Malaysia said the country had carried out a detailed probe into its nationals aboard the flight, which vanished on March 8, and could rule out their involvement.

US and European security sources said efforts by various governments to investigate the backgrounds of everyone on the flight had not, as of Monday, turned up links to armed groups or anything else that could explain the jet's disappearance.

A European diplomat in Kuala Lumpur also said trawls through the passenger manifest had come up blank.

'Refusal of help'

Malaysia's top official in charge of the search for a missing jetliner rejected criticism on Tuesday from US officials that it has not been sharing as much information as it could with foreign governments.

China too has called for better coordination in the search operation and some US officials and politicians have expressed frustration at what they see as Malaysia's refusal of help.

Malaysian Defence Minister Hishammuddin Hussein specifically defended coordination with the United States and China and said he had been in touch with his counterparts in both countries.

"This morning, I was [speaking] with [US Defence Secretary] Chuck Hagel and then I was also with my counterpart [from] China," he told Reuters.

Hishammuddin denied reports that Malaysia had discouraged the Federal Bureau of Investigation (FBI) from sending a team to Malaysia.

"I have been working with them. It's up to the FBI to tell us if they need more experts to help because it's not for us to know what they have."

Malaysian officials say they have been in touch with the FBI through the US embassy, where the agency has a permanent representative, from "day one".

"No matter what everyone says, the cooperation that I am getting for Malaysia and for what efforts I am doing, it is overwhelming," Hishammuddin said.

Two US security officials said on Monday that Malaysia had still not invited the FBI to send a team.