Malaysia Airlines plane: Oil slick is first sign that missing flight crashed into sea killing up to 239 on board

The Vietnamese air force has spotted two large oil slicks off the country's southern tip, suspected to be from the Malaysia Airlines Boeing 777 plane that went missing on Saturday.

The traces of oil were each between six miles and nine miles long, and were consistent with the kinds that would be left by fuel from a crashed jetliner, officials said.

Over two hundred passengers were on board Flight MH370 bound to Beijing from Kuala Lumpur, when it disappeared from Malaysian air traffic control screens.

Christian Kozel, 30, from Austria, and Luigi Maraldi, 37, from Italy were listed among the passengers on the flight, but were not on board, officials in both European countries confirmed on Saturday, and at least one of them had had his passport stolen.

A Foreign Ministry spokesman in Vienna said the Austrian national was safe at home, but that his passport stolen while travelling in Thailand two years ago.

No Italian passengers were on the flight, according to the country's Foreign Ministry, despite the inclusion of Maraldi's name on the list. Unconfirmed reports suggest that Maraldi's passport was also stolen.

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

"The search and rescue operations will continue as long as necessary,"he added.

The aircraft was crossing between Malaysia and Vietnam when contact broke down at 1:30am Saturday (18:40 GMT Friday), around two hours after it had taken off, according to Azaharudin Abdul Rahman, Maslaysia's civil aviation chief.

The plane expected at Beijing at 6:30am on Saturday (22:30 GMT Friday) was carrying 227 passengers, including at least five infants, and 12 crew members, the airline said.

It added there were 153 passengers from China, 38 from Malaysia, seven each from Indonesia and Australia, five from India, four from the U.S. and others from Indonesia, France, New Zealand, Canada, Ukraine, Russia, Taiwan, and the Netherlands.

There were no reports of bad weather and no obvious reason why the aircraft would have vanished from radar screens.

Ships and planes from Southeast Asian nations, including 15 air force aircraft, six navy ships and three coast guard vessels from Malaysia, continue to scour the seas.

No wreckage has yet been spotted, and Vietnamese fishermen in the area have also been asked to report any suspected sign of the missing plane.

A Vietnamese search and rescue official, Pham Hien, said the last signal detected from the plane was 120 nautical miles (140 miles or 225 km) southwest of Vietnam's southernmost Ca Mau province, which is close to where the South China Sea meets the Gulf of Thailand.

In a call with the Malaysian Prime Minister, Chinese Premier Li Keqiang urged Malaysia on Saturday to quickly and vigorously push search and rescue work for the plane, state news agency Xinhua said.

Chinese relatives of passengers on the flight angrily accused the airline of keeping them in the dark, while state media criticised the carrier's poor response.

Relatives were taken to a hotel near Beijing airport, put in a room and told to wait for information from the airline, but no one met them.

About 20 people stormed out of the room at one point, enraged they had been given no information.

Malaysia Airlines CEO Ahmad Jauhari Yahya said:"Our team is currently calling the next-of-kin of passengers and crew. Focus of the airline is to work with the emergency responders and authorities and mobilize its full support."

"Our thoughts and prayers are with all affected passengers and crew and their family members," he added.

There was no indication that the pilots sent a distress signal and the fact that there was apparently no call for help suggests that whatever happened to the flight occurred quickly, he contined.

According to a government statement, Lieutenant General Vo Van Tuan, deputy chief of staff of the Vietnamese army, said the plane “lost all contact and radar signal one minute before it entered Vietnam's air traffic control”.

As 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, Malaysian Transport Minister Hishammuddin Hussein said authorities had "no information" if terrorism was the cause, but added “we are looking at all possibilities.“

Malaysian Airlines has a good safety record, as does the 777, which had not had a fatal crash in its 19-year history until an Asiana Airlines plane crashed in San Francisco in July 2013, killing three passengers, all teenagers from China.

Additional reporting by AP