Malaysia on Tuesday released raw satellite data used to determine that missing Flight MH370 went down in the southern Indian Ocean, information demanded by passengers' relatives who are frustrated over the failure to find any wreckage.

The Department of Civil Aviation (DCA) said it had worked with Inmarsat to provide 47 pages of data communication logs recorded by the British satellite operator, as well as explanatory notes for public consumption.

Analysts said it would take time to draw any conclusions from the raw, highly technical data.

The families of the 239 passengers and crew on board the Malaysia Airlines plane had demanded the information be made public after a massive and costly search for the flight, which mysteriously diverted from its Kuala Lumpur-Beijing route 11 weeks ago, found nothing.

Officials, relying in part on the Inmarsat data, have said they believe the plane ended up over the southern Indian Ocean where it crashed into the sea, possibly after running out of fuel.

The numerical data used the Doppler effect -- the change in frequency of waves from a moving object -- to decipher the Boeing 777's final flight path.

Inmarsat's interpretation of the data was subsequently verified by the international investigation team, which includes the DCA and the air safety boards of Britain, China and the United States.

But, with no sign of the plane found since its disappearance on March 8, relatives and friends are sceptical.

"The first thing we're going to expect feedback on is does the data look right," Sarah Bajc, whose partner Philip Wood was on the missing jet, told CNN.

"Is it as complete as we're being led to believe it is?" the American said.

- Another flight route? -

Bajc and other relatives said in a May 20 report to the governments of Malaysia and Australia, which is coordinating the search effort, that they wanted to know if another flight path had been possible.

"There is no mention on why they are so sure the Inmarsat data is highly accurate and reliable, to the extent that they have thrown all resources there," the report said.

Greg Waldron, Singapore-based managing editor with aviation publication group Flightglobal, said the satellite data was consistent with what Inmarsat had previously revealed.

"Basically it shows the timings of the handshakes of the plane with the satellite over the Indian Ocean," he said.

"But I would not dare to guess if they are searching in the right place. The fact that they are using this type of data shows how desperate the search for the plane is."

The DCA has previously stressed that satellite data was just one of several elements being examined by investigators.

Malaysian authorities have been tight-lipped on details, saying they can only divulge information once it has been verified and when its release will not affect investigations into the plane's disappearance.

Australia has committed up to US$84 million towards the search operation over two years.

One phase of the search is set to end this week. Ocean Shield, an Australian ship that has been deploying a US Navy mini-sub to scour the ocean depths, is expected to leave the search area on Wednesday and then return to Perth to demobilise the submersible.

The next phase will involve using sophisticated equipment to scan the unmapped ocean bed. Commercial negotiations are underway to engage contractors to do this work, according to Australian officials.