Three separate electronic signals have been detected in the hunt for the black box from the missing Malaysia Airlines jet, Flight MH370.
A Chinese ship detected a pulse signal for a second time after hearing it earlier on Saturday.
Investigators have warned the signals are yet to be confirmed as coming from a black box recorder and should not be treated as such "until such time as we can provide an unequivocal determination".
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The latest signal was found in a different area being searched by international teams. It is around 220 miles south of the closest of the three areas searched.
A British naval ship, HMS Echo, is heading to the are to help with the search.
The signal had a very specific frequency, 37.5 kilohertz (cycles per second). It is chosen as a signal for a black box because it stands out from other frequencies. Nothing else that lives in the sea could naturally make that sound.
“I have been advised that a series of sounds have been detected by a Chinese ship in the search area," said the Australian Chief Coordinator of the Joint Agency Coordination Centre, Air Chief Marshal Angus Houston.
"The characteristics reported are consistent with the aircraft black box. A number of white objects were also sighted on the surface about 90 kilometres from the detection area.
"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.
"I assure you that we will follow up and exhaust every credible lead that we receive."
Malaysia's civil aviation chief, Azharuddin Abdul Rahman, confirmed that the frequency emitted by MH370's black box was 37.5 kilohertz and said authorities were trying to verify the report.
The reporter, speaking to Chinese broadcaster CCTV, said the signal was first detected on Friday, intermittently for about 15 minutes. But then it was detected again Saturday morning, every second for 90 seconds.
The area where the supposed pulse was detected is an underwater mountain range similar to the Usambara mountains, up to 8,200 feet in depth.
Australian Defence Minister David Johnston had earlier urged caution. "This is not the first time we have had something that has turned out to be very disappointing," he told ABC television.
The longer the black box flight recorder remains unfound, the shorter the window of time investigators are working with.
With the battery due to run out on Monday or Tuesday next week, the likelihood that the device will be found is declining rapidly.
Ships have sighted a number of objects in the massive search area, but none have been associated with the missing plane.
If the black box's battery runs out before searchers locate it, the device could not be found for years.Suggest a correction