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* Pulse signal picked up in southern Indian Ocean -Xinhua
* Up to 13 planes, 11 ships scouring ocean on Saturday
* Battery of plane's black box likely to run out soon
* Malaysia starts investigation into disappearance of plane
By Siva Govindasamy and Swati Pandey
KUALA LUMPUR/PERTH, Australia, April 5 (Reuters) - A Chinese patrol ship hunting for a missing Malaysia Airlines jetliner detected a pulse signal in the south Indian Ocean on Saturday, the state news agency Xinhua reported, in a possible indicator of the underwater beacon from a plane's "black box".
Australian search authorities said such a signal would be "consistent" with a black box, but both they and Xinhua stressed there was no conclusive evidence linking the "ping" to Flight MH370, which went missing on March 8 with 239 people aboard shortly after taking off from Kuala Lumpur for Beijing.
A black box detector deployed by the vessel Haixun 01 picked up the "ping" signal with a frequency of 37.5kHz per second - the same as emitted by flight recorders - at about 25 degrees south latitude and 101 degrees east longitude, Xinhua said.
Xinhua also reported that a Chinese air force plane had spotted a number of white floating objects in the search area.
Dozens of ships and planes from 26 countries are racing to find the black box recorders before their batteries run out.
Up to 10 military planes, three civilian jets and 11 ships are scouring a 217,000-sq-km (88,000-sq-mile) patch of desolate ocean some 1,700 km (1,060 miles) northwest of Perth, Australia, near where investigators believe the Boeing went down.
"The characteristics reported (by the Chinese vessel) are consistent with the aircraft black box," Retired Air Chief Marshal Angus Houston, head of the Australian agency coordinating the operation, said in a statement.
"However, there is no confirmation at this stage that the signals and the objects are related to the missing aircraft," he said, adding his agency was seeking more information from China.
SONAR EQUIPMENT
Authorities have not ruled out mechanical problems as a cause of the plane's disappearance, but say the evidence, including loss of communications, suggests it was deliberately diverted thousands of kilometres (miles) from its set route.
Sonar equipment on two ships joining the search may help find the black box voice and data recorders that are key to unlocking what happened on the flight.
Australian authorities said the so-called Towed Pinger Locator would be pulled behind navy ship HMAS Ocean Shield, searching a converging course on a 240-km (150-mile) track with British hydrographic survey ship HMS Echo.