The oil slicks were spotted late on Saturday off the southern tip of Vietnam by air force planes dispatched to search for the missing Malaysia Airlines Boeing 777 flight.

"Two of our aircraft sighted two oil slicks around 15 to 20 kilometers (10-12 miles) long, running parallel, around 500 meters apart from each other," deputy chief-of-staff of the Vietnamese army, Vo Van Tuan, told state-run VTV.

The sighting of the oil is the first indication the missing plane could have gone down in the waters between northern Malaysia and southern Vietnam.

There is no confirmation the find was related to the missing plane, although the Vietnamese government released a statement saying the oil slicks were consistent with the kind that would be produced by the fuel tanks of a crashed plane.

International search and rescue operations were launched early Saturday morning after flight number MH370, lost contact with air traffic control.

Chinese state television said two rescue ships had been dispatched to the South China Sea to help search efforts. Malaysia, the Philippines and Vietnam are also taking part in the search for the plane by sea and by air.

The Boeing 777-200 had set off from Kuala Lumpur shortly after midnight local time, (16:41 UTC), carrying 239 people, according to carrier Malaysia Airlines. Subang air traffic control officials lost contact with the jet some two hours later.

"Malaysia Airlines is currently working with the authorities who have activated their search-and-rescue teams to locate the aircraft," the carrier said.

The plane had been due to land in Beijing at 6.30 a.m. local time (22:30 GMT).

Fate of passengers unknown

In a statement, airline CEO Ahmad Jauhari Yahya said the flight was carrying a total number of 239 passengers and crew - comprising 227 passengers (including 2 infants) and 12 crew members.

"(The) focus of the airline is to work with the emergency responders and authorities and mobilize its full support," Ahmad Jauhari said. "Our thoughts and prayers are with all affected passengers and crew and their family members." The airline added that it was contacting next of kin of those on board.

A later statement by the carrier said it had not been ascertained if the flight had crashed, the plane having last had contact with Malaysian air traffic controllers 120 nautical miles (222 kilometers) off the east coast of the Malaysian town of Kota Bharu.

Malaysia Airlines said there were at least 14 nationalities on board, including 152 people from China, 38 Malaysians, seven Indonesians, six Australians, five Indians, four French and three Americans, including an infant.

"This news has made us all very worried," said Chinese Foreign Minister Wang Yi in Beijing. "We hope every one of the passengers is safe. We are doing all we can to get more details."

Emergency response

Chinese and Vietnamese media earlier reported that an unspecified signal had been picked up from the plane near Cape Ca Mau, 250 km (155 miles) southwest of Ho Chi Minh city, but a Vietnamese maritime search-and-rescue official later said that was not true.

Xinhua said the Chinese embassy in Malaysia had formed an emergency team, led by the ambassador, to respond to the incident.

A spokesman for Beijing airport said it had activated an emergency response system.

Malaysia Airlines has 15 Boeing 777-200 jets in its fleet of about 100 planes. As Malaysia's national flag carrier and one of Asia's largest airlines, it flies to 87 destinations across six continents, transporting nearly 37,000 passengers daily.

Like the airline, the Boeing 777 has a good record, with only one previous fatal crash in its 19-year history.

Three Chinese teenagers died in July last year after an Asiana Airlines 777 crashed in San Francisco.

rc, cpp/se (AFP, AP, Reuters)