PERTH, Australia - A sea and air fleet was scouring the vast Indian Ocean on Monday for further underwater signals in the hunt for a missing Malaysian airliner before the plane's black box batteries run out.
Three separate signals have been detected so far raising hopes of solving the mystery of Flight MH370.
Up to nine military planes, three civil planes and 14 ships were to take part in Monday's operation, Australia's Joint Agency Coordination Centre (JACC) said.
Angus Houston, head of the Australian-led search mission, said Sunday the signal detections were being taken "very seriously" as time ticked down on the the black box tracking beacons.
He said Chinese vessel Haixun 01 had twice picked up an underwater signal on a frequency used for the plane's flight data and cockpit voice recorders - once for 90 seconds on Saturday and another more fleeting "ping" on Friday a short distance away.
A third "ping" was also being scrutinised, 300 nautical miles away, by the Australian vessel Ocean Shield.
"This is an important and encouraging lead but one which I urge you to continue to treat carefully," Houston told reporters of developments on Sunday.
"We are working in a very big ocean and within a very large search area." Britain's Ministry of Defence confirmed late Sunday that the HMS Echo, equipped to detect a black box, had arrived in the area where the Chinese had reported a ping.
"It will start its work to find the black box in the next hour," the spokeswoman told AFP.
Houston said Australian ship Ocean Shield - also equipped with a black box locator - and Australian air force planes were being diverted to the area to help discount or confirm the Chinese signals.
The search area was expected to be approximately 234,000 square kilometres on Monday, the JACC said in a statement, predicting good weather throughout the day.
The Malaysia Airlines Boeing 777 with 239 people aboard vanished on March 8 during a flight from Kuala Lumpur to Beijing and is believed to have crashed into the southern Indian Ocean.
No debris has yet been found despite extensive aerial and sea searches, prompting authorities to switch to undersea acoustic surveillance in hopes of finding the aircraft.
Houston said the Chinese finding was more promising.
"I think the fact that we've had two detections, two acoustic events in that location, provides some promise which requires a full investigation," he said.