Two ships central to the hunt for missing Malaysia Airlines Flight 370 are due to arrive in the search area in the coming hours amid hope that a new clue to the plane's whereabouts may be imminent.

A British Royal Navy survey ship, HMS Echo, will be conducting a specific search today, a spokesperson for the Australian Defence Force told GNN.

The Ocean Shield, an Australian naval vessel equipped with special US technology designed to detect the pings from the flight recorders, is also due to arrive in the search area overnight Thursday to Friday.

The spokesperson, who is

not authorized to speak to the media, told GNN there would be a "big" operational announcement today by retired Air Chief Marshal Angus Houston, the head of the Australia's new Joint Agency Coordination Centre, who has been tasked with overseeing the search effort.

It's not yet clear what that announcement might be, but any progress will likely be welcomed by the despairing relatives of the 239 people aboard the plane, which vanished nearly four weeks ago.

The Ocean Shield is equipped with the TPL-25, a giant underwater microphone that will listen for the pings from the flight data recorders and the Bluefin-21, an underwater robot that can scour the ocean bed, looking for signs of wreckage.

But until searchers find a confirmed piece of debris from the plane, which would give them an idea of where the wreckage might be located, the sophisticated listening technology is of little use.

Meanwhile, Malaysian Prime Minister Najib Razak, who is touring Australia, yesterday vowed "we will not rest" until the fate of flight MH370 is known, as Australia called it "the most difficult search in human history".

"We want to find answers. We want to provide comfort to the families and we will

not rest until answers are indeed found," Najib said, as he thanked those involved in the eight-nation search.

Despite extensive scouring of the remote southern Indian Ocean, no debris that would indicate a crash site has been found, with time running out to locate the plane's "black box" which only emits a signal for around 30 days.

Investigators are yet to provide an explanation of why the plane flew way off course or pinpoint exactly where it ended up. Officials say that an analysis of the available data suggests the jet's journey finished in the southern Indian Ocean.