Missing Malaysian jet: Most difficult search in history continues

“The Royal Navy hydrographic ship HMS Echo also operated in the northern area searching for sonic transmissions from the flight data recorder. One alert was experienced but discounted. False alerts may be experienced from biological sources such as whales or interference from shipping noise,” it added.

Malaysia Airlines flight MH370 vanished mysteriously about an hour after taking off from Kuala Lumpur shortly after midnight March 8.

The Boeing 777-200ER was scheduled to land in Beijing the same day. The 227 passengers on board included five Indians, 154 Chinese and 38 Malaysians.

Earlier Thursday, Australian Prime Minister Tony Abbott said the ongoing search for missing Malaysia Airlines flight MH370 is "the most difficult in human history", while reiterating his promise to the families of those on board that his country will continue the current search process as best as they can.

In a joint press conference with his visiting Malaysian counterpart Najib Razak, Abbott told reporters this was probably the most difficult search ever undertaken, but "as far as Australia is concerned, we are throwing everything we have" to search for the aircraft, Xinhua reported.

"This is a very tough time for Prime Minister Najib... the search area is moving north, but it's still a remote and inaccessible area... it's the most difficult in human history," said the Australian leader.

He also asked the families of those on board the lost jet to be "patient", saying Australia and the multinational forces will not let them down and would provide the warmest possible welcome if they wanted to come to Australia.