Planes and ships are now concentrating their search for a missing Malaysian airliner in an area of the southern Indian Ocean where a civil aircraft spotted debris, including a wooden shipping pallet, on Saturday.
A New Zealand military plane diverted to the location on Saturday found only seaweed.
The sighting of debris came on the same day that China released satellite images taken several days ago of another large object floating in the same area, about 2,500 kilometers west of the Australian city of Perth.
Australian Prime Minister Tony Abbott said Sunday that there is "increasing hope" the sightings could lead to a breakthrough into finding the missing Malaysia Airlines jet with 239 people on board.
Australian images shot last week also showed two large objects in the water. But investigators have yet to find the debris that may or may not be from Flight 370.
The Boeing 777 disappeared 15 days ago while traveling from Kuala Lumpur to Beijing. There has been no firm evidence so far of what happened to the jet.
Investigators are not ruling out anything, including catastrophic mechanical failure and terrorism. They say it is possible someone with knowledge of planes diverted it far off course.
Twenty-six nations have been hunting for the plane across an area covering more than 7 million square kilometers, from Kazakhstan to the southern Indian Ocean.