A Malaysia Airlines Boeing 777-200ER MH370 vanished en route from Kuala Lumpur to Beijing in the early hours of March 8 with 239 passengers and crew on board. No trace of the plane has been found.
China has called for better coordination in the search operation for Malaysia Airlines missing plane now involving 26 countries, while some U.S. 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 (U.S. Defense 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 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 U.S. 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 U.S. security officials said on Monday that Malaysia had still not invited the FBI to send a team.
One source in Kuala Lumpur familiar with the investigation said an FBI team was in Malaysia to help with the probe. But another source familiar with the matter confirmed that no one had arrived from the United States to reinforce the FBI presence in the country.
An unprecedented search for the missing Malaysia Airlines MH370 flight now stretches across Asia, from the Caspian Sea to the southern Indian Ocean.
Investigators are convinced that someone with deep knowledge of the Boeing 777-200ER and commercial navigation diverted the jet, carrying 227 passengers and 12 crew, perhaps thousands of miles off course.
The FBI has extensive experience in investigating plane disasters, including the crashes off the U.S. east coast of TWA Flight 800 in 1996 and Egyptair Flight 990, en route from Los Angeles to Cairo, in 1999.
In the case of Egyptair 990, the FBI helped air safety investigators establish that the crash was caused by a suicidal co-pilot.
In the TWA 800 case, the FBI conducted a lengthy investigation that eventually helped the National Transportation Safety Board discredit theories that the plane was hit by a missile, but instead was brought down by a freak accident involving overheated fuel.
India, which has suspended search operations for the Malaysian plane pending a review of the satellite data, has said it had no complaints with the sharing of information.
"I think they (Malaysia) are sharing all the information. Every country has the capability up to their own airspace ... So the information they have, they have shared," said Acquino Vimal, India's deputy high commissioner to Malaysia..
"I am yet to hear anything from our operational people saying that we are not getting information."
The Malaysia Airlines jet disappeared in a region beset by rivalries over military capabilities and where sovereignty can be a grey issue.
Furthermore, the need to co-operate has cast a potentially embarrassing light on regional surveillance capabilities, especially where the ability of nations to watch each other's airspace is concerned.
In Australia, a defence industry source said that any available information from its powerful radars pointing out to the Indian Ocean would likely be passed on to Malaysia in a "highly sanitised way" to conceal its origins and appease any concerns about Australian monitoring of neighbouring airspace.