Indonesian officials say they are sending teams to investigate reports of smoke on an island in the area where AirAsia flight QZ8501 has gone missing.
The multinational search for the plane has entered a third day, with the operation area now widened to cover 13 zones over land and sea.
The Airbus A320-200, carrying 162 people from Surabaya in Indonesia to Singapore, disappeared on Sunday.
The pilot's last contact was a request to divert around bad weather.
Indonesian officials say air traffic control had approved one request, to veer left, then gave clearance to a second request for permission to climb two to three minutes later.
No reply was received and the plane then disappeared from radar. No trace has yet been found.