AirAsia flight QZ8501, which went missing mid-flight on Sunday morning carrying 162 passengers, is thought to have crashed into the sea, an Indonesian official says.
Search and rescue crews suspended operations overnight after the plane went missing just after midnight, UK time, on Sunday.
One Briton is aboard the missing flight, understood by Channel 4 News to be Chi Man Choi.
The Indonesian AirAsia aircraft disappeared after its pilot failed to get permission to fly higher to avoid bad weather during a flight from the Indonesian city of Surabaya to Singapore.
Flight QZ8501 did not issue a distress signal before it disappeared over the Java sea.
“Based on our coordinates, we expect it is in the sea, so for now (we think) it is on the sea floor,” Soelistyo, head of Indonesia’s search and rescue agency, told reporters.
An Australian aircraft reported spotting “suspicious objects” about 700 miles away from where the plan lost contact, said a Jakarta air force official quoted by the Associated Press.
Search teams were scouring an oil slick off the east coast of Belitung island near where the plane lost contact, an air force spokesman said.
Rescuers had also picked up an emergency locator signal off the south of Borneo island, but had been unable to pinpoint it.
The flight was carrying 155 Indonesians, three South Koreans, and one person each from Britain, Malaysia and Singapore. The co-pilot was French.
AirAsia’s chief executive Tony Fernandes, who also owns Premier League football team Queens Park Rangers, has flown to Indonesia to help with the search.
He said: “We are very devastated about what’s happened. It’s unbelievable. But we do not know what’s happened yet, so we’ll wait for the accident investigation to really find out what’s happened.
“Our concern right now is for the relatives and for the next of kin, there is nothing more important to us for our crew’s family, and for our passengers’ families, that we look after them.”
The incident is the third involving Malaysia this year.