A global satellite service provider says it received a signal from missing Malayisan Airlines Flight MH370 after it disappeared.

Inmarsat said that the routine and automated signals were registered on its network during its flight from Kuala Lumpur.

"This information was provided to our partner SITA, which in turn has shared it with Malaysia Airlines" it added.

Meanwhile radar-tracking evidence earlier reportedly showed the missing plane was deliberately flown towards India's Andaman Islands.

Malaysia's acting Transport Minister Hishammuddin Hussein has confirmed the search had been expanded into the Indian Ocean - on the opposite side of Malaysia from where contact with the jet was lost nearly a week ago.

He also said there was evidence of a plane turning back, but it may not have been the missing flight.

It comes as sources familiar with the investigation told Reuters the plane was flown hundreds of miles off course towards the Andaman and Nicobar Islands, a chain of isles in the Andaman Sea, which is part of Indian Ocean.

"What we can say is we are looking at sabotage, with hijack still on the cards" a Malaysian police source told Reuters.

After scouring the seas around the Andaman Islands, India has also started searching hundreds of small, uninhabited islands in the region.

Only 37 of the 572 islands in the atoll are inhabited. Most are Indian territory, but a small number in the north belong to Burma.

It comes as Chinese researchers reportedly detected an "earthquake wave" in the ocean between Malaysia and Vietnam around an hour-and-a -half after the plane last made contact.

"The seafloor event could have been caused by the plane possibly plunging into the sea" the scientists told China's state news agency Xinhua.

Dismissed reports of extra flight time

In his news conference, Mr. Hishammuddin refused to address media reports, citing unidentified US officials, that the plane, which was carrying 239 people, had flown for hours after vanishing from civilian radar.

The US reports were based on information that the plane's communication system continued to "ping" a satellite for up to four hours after it disappeared.

The possibility that the plane flew long after its last confirmed contact opens the possibility that one of the pilots, or someone with flying experience, wanted to hijack the plane for some later purpose, kidnap the passengers or commit suicide by plunging the aircraft into the sea.

The US Navy 7th Fleet said it was moving its ships, the USS Kidd and the USS Pinckney, towards the Indian Ocean.

Much of the early search for the Boeing 777 has been focused east of Malaysia in the South China Sea, where the Beijing-bound plane last made contact about an hour after taking off from Kuala Lumpur.

Vietnam, which has been heavily involved in the search from the start, has downgraded its hunt in the South China Sea from emergency to regular.

Ships and planes have also been searching the Strait of Malacca, west of Malaysia, because of a blip on Malaysian military radar suggested the jet might have turned in that direction.

Aviation experts have baulked at the possibility of the missing jet flying on for hours undetected in the region, which is a hotbed of bitter territorial disputes and therefore subject to round-the clock surveillance by the competing parties.

Flying from the point where radar contact was lost in South China Sea to the Indian Ocean would have taken the plane through airspace monitored by Malaysian, Thai, Vietnamese, Chinese, Indonesian and Indian military radar.