The missing Malaysia Airlines jetliner may have turned back from its scheduled route before vanishing from radar screens, military officers said on Sunday.
The statement further deepens mystery surrounding the fate of the plane and the 239 people aboard.
More than 36 hours after the last contact with Flight MH370, flying from Kuala Lumpur to Beijing, officials said they were widening the search to cover vast swathes of sea around Malaysia and off Vietnam, and were investigating at least two passengers who may have been using false identity documents.
In a sign that Malaysia’s airport controls may have been breached, Prime Minister Najib Razak said security procedures were being reviewed.
“We will enhance them if necessary, because we still do not know the cause of the incident,” he told reporters.
Despite dozens of military and civilian vessels and aircraft criss-crossing waters beneath the lost plane’s flight path, no wreckage has been found, although oil slicks have been reported in the sea south of Vietnam and east of Malaysia.
The passenger manifest issued by the airline included the names of two Europeans – Austrian Christian Kozel and Italian Luigi Maraldi – who, according to their foreign ministries, were not on the plane. Both had apparently had their passports stolen in Thailand during the past two years.
The BBC reported that the men using their passports had purchased tickets together and were flying on to Europe from Beijing, meaning they did not have to apply for a Chinese visa and undergo further checks.
An employee at a travel agency in Pattaya, in Thailand, told Reuters the two had purchased the tickets there.
Meanwhile, U.S. and European security officials said there was no proof of foul play and there could be other explanations for the use of stolen passports.