An Indonesian woman wipes her eyes while holding a family picture of passengers outside the crisis center set up at Juanda International Airport in Surabaya on Monday.?MANAN VATSYAYANA / AFP

International search planes and ships scouring Indonesian waters for a missing AirAsia plane focused on a patch of oil for possible clues on Monday.

Search efforts later ended for a second day after Indonesia's National Search and Rescue Agency chief Bambang Soelistyo said that the plane is probably at the bottom of the sea.

The search area will be widened on Tuesday.

Australia, Singapore and Malaysia joined the Indonesia-led hunt as relatives waited for news of loved ones more than a day after Flight QZ8501 disappeared over the Java Sea with 162 people aboard.

The Airbus A320-200 lost contact en route from Surabaya in Indonesia to Singapore on Sunday after the crew requested a change of flight plan due to stormy weather.

It is the third crisis for a Malaysian carrier this year.

Indonesian Air Force spokesman Hadi Tjahjanto said the search on Monday concentrated on an oil patch spotted off Belitung island in the Java Sea, across from Kalimantan on Borneo.

"We are making sure whether it is avtur (aviation fuel) from the AirAsia plane or from a vessel, because that location is a shipping route," he said.

Indonesian Vice-President Jusuf Kalla said an object spotted at sea did not come from the plane.

Ships and aircraft searched an area where the sea is 40 to 50 meters deep, he said, adding that Indonesia is coordinating with other countries to borrow any equipment needed to scour the seabed.

Distraught relatives spent Sunday night in Surabaya hoping for news of loved ones as the international search effort expanded.

Intan, 28, said Indonesia needs overseas help to find the plane, which was carrying her brother and his family and friends.

"My hope is Indonesia seeks as much help as possible from other countries. Don't claim 'We have sophisticated technology' — just ask other countries, because they are better equipped," she said as Jakarta welcomed offers of help from its neighbors.

One Indonesian family of 10 had a miraculous escape when it arrived too late to catch the flight.

"Maybe it is all God's plan that my family and I were not on the flight. It was a blessing in disguise," said Christianawati, 36.

AirAsia said 155 of those on board are Indonesian, with three South Koreans and one person each from Singapore, Malaysia, Britain and France. The Frenchman is the co-pilot.

Air traffic controllers lost contact with the twin-engine aircraft about an hour after it left Surabaya's Juanda International Airport at about 5:35 am on Sunday.

The last communication from the cockpit to air traffic control was a request by one of the pilots to increase altitude because of rough weather. Air traffic control was not able to grant the request immediately because another plane was in the airspace.

By the time clearance could be given, Flight 8501 had disappeared.

AFP — AP