PERTH (AFP) - Australian Prime Minister Tony Abbott said on Sunday there was "increasing hope" of finding missing Malaysia Airlines Flight MH370, after a plane spotted unidentified debris including a wooden pallet in the Indian Ocean search site.
Visual contact with the debris was made on Saturday, as fresh Chinese satellite images emerged showing a large floating object in the same remote region around 2,500 kilometres south-west of Perth.
"It's still too early to be definite," Mr Abbott told reporters during a visit to Papua New Guinea.
"But obviously we have now had a number of very credible leads and there is increasing hope - no more than hope, no more than hope - that we might be on the road to discovering what did happen to this ill-fated aircraft."
Resources for the international search effort triggered by the disappearance of the Boeing 777 on March 8 have flooded into the inhospitable stretch of southern ocean since Mr Abbott released satellite images on Thursday showing possible wreckage.
The precise nature of the debris sighted on Saturday was unclear, but Mr Abbott described "a number of small objects fairly close together... including, as I understand it, a wooden pallet."
The Australian Maritime Safety Authority (AMSA), which is coordinating operations in the search zone, was cautious in its appraisal of the new findings.
The small "objects of interest" were initially identified by observers on one of the civil aircraft engaged in the search, AMSA said in a statement.
An air force P3 Orion aircraft with specialist electro-optic observation equipment was diverted to the same location, but only reported sighting "clumps of seaweed," the statement said.
"Further attempts will be made today to establish whether the objects sighted are related to MH370," it added.
The Orion dropped a marker buoy to track the movement of the material and a merchant ship in the 36,000-square-kilometre search area was tasked with following up the sighting.
Although the findings remain circumstantial, the satellite images and sightings of recent days have galvanised a hunt that had become mired in confusion and frustration.
A total of eight planes, including three P3 Orions and a US Navy P8 Poseidon, were taking part in Sunday's operations out of Perth, and will be joined Monday by two newly arrived Chinese military Ilyushin IL-76 aircraft.
"Obviously the more aircraft we have, the more ships we have, the more confident we are of recovering whatever material is down there," Mr Abbott said.
If the plane did crash in the ocean, investigators are hoping to identify the impact site before the plane's black box stops emitting tracking signals - usually after 30 days.
The flight recorder will be crucial in solving the mystery of what caused the Boeing 777 with 239 passengers and crew to suddenly veer off course over the South China Sea en route to Beijing.
Satellite and military radar data suggest the plane backtracked over the Malaysian peninsula and then flew on - possibly for hours - either north into South and Central Asia, or south over the Indian Ocean.
The question of what happened on board has become a topic of unbridled speculation, with Malaysian investigators standing by their assessment that the plane was deliberately diverted by someone on it.
Three scenarios have gained particular traction: hijacking, pilot sabotage, and a sudden mid-air crisis that incapacitated the flight crew and left the plane to fly on auto-pilot for several hours until it ran out of fuel and crashed.
The long, largely fruitless search for the aircraft has been especially agonising for the relatives of the 227 passengers - two thirds of whom were Chinese - and 12 crew.
The grief and frustration boiled over Saturday at a hotel in Beijing when police had to restrain angry family members confronting Malaysian officials they accused of withholding information.
Although the plane's disappearance is already the subject of a criminal investigation, Mr Abbott stressed that the search was essentially a "humanitarian" exercise.
"We owe it to the almost 240 people on board the plane, we owe it to their grieving families, we owe it to the governments of the countries concerned, to do everything we can to discover as much as we can about the fate of MH370," he said.
China has dispatched seven ships to the hunt for the plane, adding to British and Australian naval assets involved.
The latest Chinese satellite images showed an object measuring 22.5 metres by 13 metres.
Mr Abbott said it was "consistent" with one of the objects identified in the Australian satellite images, but it was not clear if they were believed to be the same.
"Hope we find something today," Malaysian Transport Minister Hishammuddin Hussein said in a text message to AFP.