In the search for the plane in the Indian Ocean, a Chinese patrol ship Haixun 01 picked up two signals, one on Friday and another yesterday, that were only 2 kilometers apart, authorities said.
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.
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.
The black box can provide audio record of what happened on March 8 before the Beijing-bound Malaysia Airlines jet with 239 people, including five Indians, crashed in the southern Indian Ocean.
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.
Ocean Shield, which has a high-tech pinger locator borrowed from the US Navy, will continue to pursue the sound it heard. If that lead turns cold, it will move to the other detection area, a journey that will take at least a day, Houston said.
The signals are the latest leads in a huge, multinational hunt for Flight 370. Investigators have so far been unable to say why the plane flew far off course or where exactly it ended up.
Also yesterday, a Chinese air force plane spotted a number of white floating objects in the search area. The plane photographed the objects over a period of 20 minutes after spotting them at 11:05 local time. The detection has been reported to the JACC.
Some 10 military planes, two civil jets and 13 ships took part in today's search operations to trace the plane.
The search area is approximately 216,000 square km, about 2,000 km northwest of Perth. It is about 300 km farther from the western coastal city than the area searched on the day before.
The mystery of the missing plane continued to baffle aviation and security authorities who have so far not succeeded in tracking the aircraft despite deploying hi-tech radar and other gadgets.
The desperate efforts to trace the signals come as new details emerged about the missing plane's likely path on the night it vanished.
More detail has been added to the flight path calculated by investigators, a senior Malaysian government source told CNN.
After reviewing radar track data from neighbouring countries, officials have concluded that the passenger jet curved north of Indonesia before turning south toward the southern Indian Ocean. Its path took it around Indonesian airspace.
The plane did not fly over Indonesia or its airspace, the source said.