KUALA LUMPUR, Malaysia - Vietnamese ships and planes hunting for a missing Malaysian jetliner have found no wreckage close to where they spotted two large oil slicks.

The Boeing 777 carrying 239 people disappeared off radar screens early Saturday less than an hour after taking off from Kuala Lumpur bound for Beijing.

An international fleet of planes and ships has been scouring the waters between Malaysia and Vietnam for signs of the plane.

They spotted two oil slicks late Saturday, which authorities say might have been from the plane.

Deputy transport minister Pham Quy Tieu said no wreckage had been seen in the vicinity of the slicks early Sunday, but that the search was continuing.

In Kuala Lumpur, Malaysia's deputy civil aviation authority chief, Azhaddin Abdul Rahman, told reporters that the oil slick find had yet to be verified.

He said that the air search, suspended for the night, resumed Sunday, in addition to a sea search that continued through the darkness.

The jet's disappearance was especially mysterious because it apparently happened when the plane was at cruising altitude, not during the more dangerous phases of takeoff or landing.

Just 9 percent of fatal accidents happen when a plane is at cruising altitude, according to a statistical summary of commercial jet accidents done by Boeing.

Malaysia Airlines CEO Ahmad Jauhari Yahya said there was no indication the pilots had sent a distress signal. That might mean that whatever trouble befell the plane happened so fast the crew did not have time to broadcast even a quick mayday.

The lack of a radio call ''suggests something very sudden and very violent happened,'' said William Waldock, who teaches accident investigation at Embry-Riddle Aeronautical University in Prescott, Ariz.

The plane was last inspected 10 days ago and found to be ''in proper condition,'' Ignatius Ong, CEO of Malaysia Airlines subsidiary Firefly airlines, said at a news conference.

Two-thirds of the jet's passengers were from China. The rest were from elsewhere in Asia, North America and Europe.

Asked whether terrorism was suspected, Malaysian Prime Minister Najib Razak said authorities were ''looking at all possibilities, but it is too early to make any conclusive remarks.''

Contributing to fears of foul play was word from foreign ministries in Italy and Austria that the names of two citizens listed on the flight's manifest matched the names on two passports reported stolen in Thailand.

Italy's Foreign Ministry said an Italian man who was listed as a passenger, Luigi Maraldi, was traveling in Thailand and was not aboard the plane. It said he reported his passport stolen last August.

Austria's Foreign Ministry confirmed that a name listed on the manifest matched an Austrian passport reported stolen two years ago. It said the Austrian was not on the plane but would not identify the person.

The amount of time needed to find aircraft that go down over the ocean can vary widely. Planes that crash into relatively shallow areas, like the waters off Vietnam where the Malaysian jet is missing, are far easier to locate and recover than those that plunge deep into undersea canyons or mountain ranges.

At Beijing's airport, authorities posted a notice asking relatives and friends of passengers to gather at a nearby hotel to await further information. A woman aboard a shuttle bus wept, saying on a mobile phone, ''They want us to go to the hotel. It cannot be good.''

Nan Jinyan, a relative of a Beijing hospital staffer who was among the passengers, said all the information they were getting was from the Internet and the news.

Passengers' loved ones were escorted into a private area at the hotel, but reporters were kept away. A man in a gray hooded sweatshirt later stormed out complaining about a lack of information. The man, who said he was a Beijing resident but declined to give his name, said he was anxious because his mother was aboard the flight with a tourist group.

''We have been waiting for hours and there is still no verification,'' he said.

The plane was last seen on radar at 1:30 a.m. (1730 GMT Friday) above the waters where the South China Sea meets the Gulf of Thailand, authorities in Malaysia and Vietnam said.

Lai Xuan Thanh, director of Vietnam's civil aviation authority, said air traffic control in the country never made contact with the plane.

The South China Sea is a tense region with competing territorial claims that have led to several low-level conflicts, particularly between China and the Philippines. That antipathy briefly faded Saturday as China, the Philippines, Vietnam, Singapore and Malaysia all sent ships and planes to the region.

Malaysia had dispatched 15 planes and nine ships to the area, Najib said.

The U.S. Navy was sending a warship and a surveillance plane, while Singapore said it would send a submarine and a plane. China and Vietnam also sent aircraft to help in the search.

The plane was carrying 227 passengers and 12 crew members, the airline said. The manifest included 152 passengers from China, 38 from Malaysia, seven from Indonesia, six from Australia, five from India, three from the U.S., and others from Indonesia, France, New Zealand, Canada, Ukraine, Russia, Taiwan and the Netherlands.