About 12 hours after EgyptAir flight MS804 disappeared over the eastern Mediterranena Sea, a search and rescue mission was ongoing with ships and planes from France, Greece and Egypt.

The search continued after reports that wreckage had been found in the Mediterranean Sea turned out to be false, according to airline vice-chairperson Ahmed Adel.

"We stand corrected on finding the wreckage because what we identified is not a part of our plane. So the search and rescue is still going on," Adel said on CNN.

The Airbus A320 with 66 people on board was en route from Paris to Cairo when it disappeared from radar around 2.30am (8.30am Malaysian time) yesterday, about 280km from the Egyptian mainland.

Egypt's Civil Aviation Ministry said the jet had crashed, and there was widespread speculation about the cause, which was still unclear. A crisis unit has been set up in Cairo, where Civil Aviation Minister Sherif Fathy said it was unlikely that the plane went down due to technical problems.

"The situation may indicate that the likelihood of a terrorist work is far higher than the likelihood that the plane developed a technical failure," he said. "But we have to wait for investigations," he added.

A US official said at this early stage there was no evidence suggesting there was an explosion, but it was too early to rule anything out.

Flight MS804 was flying at a height of 11,300 metres when it disappeared 45 minutes before its expected landing in Cairo, Egyptair said.

The pilots did not make contact when they left Greek airspace as is customary, the country's aviation authority said.

Egyptair said Mohammed Said Ali Shaqir was the plane's pilot, and said he had over 6,000 hours of flights logged, more than 2,000 of them on Airbus A320s. The co-pilot had 2,766 flight hours logged, the company said.

The plane was delivered to the operator in 2003, manufacturer Airbus said, adding that it had accumulated some 48,000 flight hours.

The highest official to speculate about what could have caused the sudden crash was French President Francois Hollande.

"Once we have the truth we can draw conclusions, whether this is an accident or another hypothesis that everyone has on their minds, perhaps a terrorist hypothesis," Hollande said. "But at this stage we must put first our solidarity with the families and into the search for a cause."

The jet was carrying 56 passengers, seven crew members and three security officers. Passengers included 30 Egyptians, 15 French nationals, two Iraqis and one each from Britain, Belgium, Kuwait, Saudi Arabia, Sudan, Chad, Portugal, Algeria and Canada, according Egyptair. Three children were on board.

Satellite imagery

Egypt and France opened separate investigations into the accident, and Hollande and his Egyptian counterpart Abdel-Fattah al-Sissi agreed to cooperate fully. France also sent two planes and a ship to help the search.

In Brussels, US Secretary of State John Kerry offered his condolences. US President Barack Obama directed US officials to offer support and assistance.

Meanwhile, officials from multiple US agencies said that a US review of satellite imagery so far had not produced any signs of an explosion aboard the EgyptAir flight.

The US officials, who spoke on condition of anonymity to discuss intelligence matters, said the conclusion was the result of a preliminary examination of imagery and cautioned against media reports suggesting the United States believed a bomb was responsible for the crash.

Amid uncertainty about what downed the plane, Los Angeles International Airport became the first major US air transport hub to say it was stepping up security measures.

"In light of the disappearance of EgyptAir Flight MS804, we have heightened our security posture and enhanced our counter-terrorism security measures," the Los Angeles Airport police said in a statement.

At Cairo airport, a man sat on a brown leather couch crying with his hands covering his face. "How long will Egypt live if human lives are so cheap?" he said.

The mother of a flight attendant rushed out of the VIP hall where families waited in tears. She said the last time her daughter called her was Wednesday night. "They haven't told us anything," she said.

Some relatives tried to beat up a photographer working for EgyptAir who took several pictures of the families waiting in the hall. Security officials intervened and escorted him out.

In PARIS, a police source said investigators were interviewing officers who were on duty at Roissy airport on Wednesday evening to find out whether they heard or saw anything suspicious. "We are in the early stage here," the source said.

– dpa/Reuters