Aircraft from several nations swarmed over the southern Indian Ocean Monday as the search for a missing Malaysian passenger plane was energised with mounting evidence of floating objects suspected to be linked to the plane.
But the challenge of recovering the still-unidentified flotsam took on added urgency as a tropical cyclone rumbled toward the search zone, threatening to worsen already rough conditions that have thwarted spotters.
China said Monday that one of its aircraft scouring the area had seen "suspicious" debris, adding to an Australian aircraft's visual sighting Saturday of a wooden pallet alongside strapping and other debris.
France and China both released satellite information on the weekend that also indicated floating objects far off Australia's west coast -- findings that have buoyed hopes of a breakthrough in the more than two-week-old puzzle.
A growing international fleet of military and civilian aircraft has converged on the region, supported by Australian and British naval vessels tasked with retrieving any objects from the forbidding waters.
Malaysia Airlines Flight MH370 vanished without warning on March 8 after suddenly veering off course over the South China Sea en route from Kuala Lumpur to Beijing with 227 passengers and 12 crew.
- 'Clutching' at information -
Australia's Deputy Prime Minister Warren Truss cautioned against false hopes in a search that has hit a number of dead ends.
"We're just, I guess, clutching at whatever little piece of information comes along to try and find a place where we might be able to concentrate the efforts," he told national radio.
The US Navy added to the sense of an approaching denouement, ordering the dispatch of a specialised black box locator to the region, a zone around 2,500 kilometres (1,500 miles) southwest of Perth.
Recovery of the black box will be crucial to determining what happened to the Boeing 777.
Malaysia has said the plane was deliberately diverted by someone on board but the absence of firm evidence has fuelled a host of theories that have added to the anguish of family members waiting for news of their loved ones.
"This movement is simply a prudent effort to preposition equipment and trained personnel closer to the search area so that if debris is found we will be able to respond as quickly as possible since the battery life of the black box's pinger is limited," the US Seventh Fleet said.
The listening device is able to locate black boxes down to a maximum depth of 20,000 feet (6,100 metres), it said in a statement. Oceanographers say the stretch of ocean being combed for wreckage ranges from 3,000-4,000 metres deep.
The 30-day signal from the black box is due to fail in less than two weeks.
The focus of the search had initially centred on waters around Southeast Asia but swung deep into the stormy southern Indian Ocean last week after initial satellite images depicted large floating objects there.
The Australian Maritime Safety Authority (AMSA) said 10 aircraft were now involved in a search effort beefed up by the inclusion of two Chinese military aircraft which lifted off early Monday, joining Australian, US, and Japanese planes.
China has also dispatched seven ships, adding to the British and Australian naval vessels involved.
- Tropical cyclone looms -
New Zealand Air Commodore Mike Yardley said low clouds and fog continued to make the debris elusive in sorties conducted on Sunday.
"It's a very large search area, but we keep getting more information, and that weight of evidence is pointing towards the area where we're searching, so the crew is pretty upbeat that we're in the right place," he told TVNZ.
However, Tropical Cyclone Gillian which is currently hundreds of kilometres to the north is churning in the direction of the search zone.
Truss said the storm would weaken as it tracks south "but certainly it could stir up less favourable weather."
Satellite and military radar data suggest that after its last communication with air traffic authorities, the plane backtracked over the Malaysian peninsula and then flew on -- possibly for hours -- to parts unknown.
Three scenarios have emerged to explain what happened: hijacking, pilot sabotage, or a sudden mid-air crisis that incapacitated flight crew and left the plane to fly on auto-pilot until it ran out of fuel and crashed.
Two thirds of the passengers were Chinese. Their grief and frustration has repeatedly boiled over, including in weekend meetings where police had to restrain angry relatives who accused Malaysian officials of withholding information.
"Very often I feel like I'm about to go insane. My emotions are all over the place. I asked the Malaysians to give the answers and they said they couldn't," one relative said Sunday.