Questions are mounting over passport controls, as search efforts continue near Vietnam for a missing Malaysia Airlines jet. The plane carrying 239 people, including two on stolen passports, vanished on Saturday morning.
Chinese media have slammed the Malaysian response to the jet's disappearance, saying there were "loopholes" in the work of Malaysia airlines and security authorities.
"If it is due to a deadly mechanical breakdown or pilot error, then Malaysia Airlines should take the blame. If this is a terrorist attack, then the security check at the Kuala Lumpur airport and on the flight is questionable," the Global Times newspaper, which is close to China's ruling Communist Party, wrote in an editorial. Almost two-thirds of the plane's passengers came from China.
Vietnamese searches spent hours trying to track down a rectangular object, thought to possibly be the plane's door, which was spotted on Sunday during an aerial search.
"We sent two boats to where the navy plane reported seeing that object but the boats couldn't find it," Admiral Ngo Van Phat told Reuters early on Monday.
Flight MH370 disappeared in fine weather on Saturday after reaching cruising altitude en route from Kuala Lumpur to Beijing, without sending a distress signal. No debris has been found despite an extensive multinational search effort over sea and air. Dozens of aircraft and ships from Vietnam, Malaysia, Thailand, Singapore, Australia, Indonesia, China and the United States are scouring the area.
Samples have also been taken for investigation from an oil slick, discovered in the area where the plane went missing.
Shares in Malaysia Airlines fell 10-percent as trading opened on Monday morning.
Fears of foul play in the plane's mysterious disappearance have surfaced following revelations at least two of the Boeing 777's passengers boarded using passports which were reported stolen in Thailand up to two years earlier. Interpol said it was investigating the identities of all the people on board to see whether they had also used false identity documents.
Interpol confirmed the stolen passports were registered on its database, but no authorities had checked them before the flight departed, with Interpol secretary general Ronald Noble saying only "a handful of countries" routinely did so.
Malaysian authorities were reviewing security camera footage of the two people believed to have bought one-way tickets to Europe and boarded the plane using the stolen documents. Because the passports belonged to EU citizens, the passengers would not have had to obtain Chinese visas.
On Sunday, Malaysian air force chief, Rodzali Daud, said additional radar information indicated that the plane may have turned off course before it disappeared.
"We are trying to make sense of this," Daud said at a news conference. "The military radar indicated that the aircraft may have made a turn back, and in some parts this was corroborated by civilian radar."
Malaysia Airlines has a good safety record, as does the 777, which had not had a fatal crash in its 19-year history until a crash involving an Asiana Airlines plane killed three passengers last July in San Francisco.
se/ccp (AP, Reuters, AFP, dpa)