Intelligence agencies from across the world are trying to trace the true identities of two people who used fake passports to board the missing Malaysia Airlines jet, amid growing concerns that terrorists may have hijacked or bombed the flight.
Malaysian officials examining CCTV footage have found images of the pair, the Malaysian Transport Minister said. Authorities suspecting foul play may be involved continue to look over footage from Kuala Lumpur's international airport and question border guards.
“Early indications show some sort of a security lapse, but I cannot say any further right now,” an official with direct knowledge of the investigation told Reuters.
Ground controllers lost contact with flight MH370 as it travelled somewhere between Malaysia and Vietnam early Saturday morning.
It had left Kuala Lumpur bound for Beijing around two hours earlier carrying 239 people.
Late on Sunday Vietnamese authorities said they had spotted an object that they suspect is one of the plane's doors. A massive international search is yet to find a confirmed trace of the plane however.
The weather was fine, the plane was cruising at high altitude and the pilots send no distress signal before the plane disappeared - very unusual circumstances for a modern jetliner operated by a professional airline to crash, but that experts say would be consistent with an on board explosion.
Foreign ministries in Italy and Austria said the two identities on the passenger list matched two passports reported stolen in Thailand from citizens of the countries. The pair using the passports appear to have bought the tickets together.
Interpol has criticised boarder controls for having not checked the passports - that were stolen in 2012 and 2013 - against their database.
Authorities are now looking at two more possible cases of suspicious identities, the Malaysian Transport Minister said, adding that Malaysian intelligence agencies were in contact with international counterparts. He gave no more details.
Adding to speculation, Malaysian military radar indicates the missing plane turned back on itself shortly before vanishing.
Air force chief Rodzali Daud told a media conference: “The military radar indicated that the aircraft may have made a turn back and in some parts, this was corroborated by civilian radar.”
Pilots are supposed to inform the airline and traffic control authorities if a plane does a U-turn, Malaysia Airlines Chief Executive Ahmad Jauhari Yahya added. “From what we have, there was no such distress signal or distress call per se, so we are equally puzzled,” he said.
The recent developments further strengthened concerns that terrorism could be the cause of the disappearance, aviation and terrorism experts said.
One Malaysian official told Reuters the authorities were not ruling out involvement of Uighur Muslim militants in the jet's disappearance, noting that Uighurs were deported to China from Malaysia in 2011 and 2012 for carrying false passports. Last week knife-wielding Uighur separatists killed at least 29 people in a Chinese train station.
Other scenarios, including some catastrophic failure of the engines or structure of the plane, extreme turbulence or pilot error or even suicide, were also possible, experts said.
Jason Middleton, the head of the Sydney-based University of New South Wales' School of Aviation: “You're looking at some highly unexpected thing, and the only ones people can think of are basically foul play, being either a bomb or some immediate incapacitating of the pilots by someone doing the wrong thing and that might lead to an airplane going straight into the ocean.”
“With two stolen passports (on board), you'd have to suspect that that's one of the likely options.”
Just 9 percent of fatal accidents happen when a plane is at cruising altitude, according to a Boeing statistical summary of commercial jet accidents.
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.
Malaysia 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 last July in San Francisco, killing three passengers, all teenagers from China.
A total of 22 aircraft and 40 ships have been deployed to search for the aircraft by Malaysia, Thailand, Singapore, Indonesia, China and the United States, not counting Vietnam's fleet.
China’s administrator of the Civil Aviation Administration said some debris had been spotted, but it was unclear whether it came from the plane. Vietnamese authorities said they had found nothing close to two large oil slicks spotted Saturday.