New satellite calculations have put the likely location of Malaysia Airlines Flight MH370 in the same spot where Chinese patrol vessel Haixun 01 detected deep water acoustic sounds on Friday and Saturday.
In the strongest lead to date, Air Chief Marshall Angus Houston, the head of the Joint Agency Coordination Centre, said the Haixun 01 picked up sounds coming from about 4,500m down, in two locations just two kilometres apart.
The searchers are seeking the jets two black boxes, the Cockpit Voice Recorder and the Flight Data Recorder.
Finding back the black box is crucial to know what happened on March 8 before the Beijing-bound Malaysia Airlines jet with 239 people, including five Indians, crashed in the southern Indian Ocean.
Search teams are running against time as the batteries of the black box flight recorders have a life of about 30 days, meaning they will shut down in the next two days.
Two naval ships carrying sophisticated deep-sea black box detectors are being sent to the area off western Australia where the pulses were reported to try to confirm or rule out whether they were from the missing plane's flight recorders, Retired Air Chief Marshal Angus Houston told reporters.
"This is an important and encouraging lead," said Houston, the head of the Joint Agency Coordination Centre (JACC) which is leading the search.
The electronic pulses were consistent with those emitted by the pingers on an aircraft's flight data and voice recorders, he said, but haven't been verified as coming from Flight MH370.
"Sounds also travel long distances underwater," Houston said, making it difficult to ascertain their sources. If detectors were near a pinger, it would also pick up the signal for a more sustained period.
Houston also said that search authorities were informed today that Ocean Shield, an Australian naval vessel equipped with sophisticated listening equipment, has detected "an acoustic noise" in another area of the ocean.
The search co-ordinator insisted the latest developments should be treated as unverified "until such time as we can provide an unequivocal determination".
"We are working in a very big ocean and within a very large search area, and so far since the aircraft went missing we have had very few leads which allow us to narrow the search area," he said.
HMS Echo, a British navy ship equipped with advanced detection gear, is on its way to the area where the Chinese ship picked up the signals, Houston said. It is likely to arrive tonight. Australian planes are also headed to the area.