Red and white debris spotted off the coast of Indonesia's part of Borneo island is likely to be part of AirAsia flight QZ8501, an Indonesian transport official said on Tuesday.
Media quoted an air force official as saying a suspected body, luggage and a life vest were among the debris.
"As we approached, the body seemed bloated," said First Lieutenant Tri Wibowo, who was on board a Hercules during the search operation, was quoted by the Kompas.com website as saying.
The sighting of the body was not confirmed.
"The debris is red and white," Djoko Murjatmodjo, acting director general of air transportation at the transport ministry, told reporters. "We are checking if it's debris from the aircraft. It's probably from the body of the aircraft."
Based on the size and appearance of the debris, it was likely to be part of the missing jet, Murjatmodjo added.
There have been no confirmed sightings of any wreckage of the missing plane. Most of those on board were Indonesian.
Indonesia's Kompas TV showed pictures of what looked like large, angular objects floating in the sea. The largest appeared to be several metres long.