Australian Deputy Prime Minister Warren Truss says the search for the missing Malaysia Airlines jet will continue indefinitely.
China released satellite images taken several days ago of another large object floating in the southern Indian Ocean off Australia.
Australian images shot last week showed two large objects also in the water.
Investigators in the air and on the water have been unable to find the objects, which may or may not be from Flight 370.
It takes several hours for planes to reach the search area from Australia. By that time, ocean currents could have pushed the debris farther away.
The Boeing 777 with 239 people on board disappeared two weeks 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.