Officials investigating the disappearance of a Malaysian airliner with 239 people on board say radar images show the missing jet may have inexplicably turned back before vanishing.
Malaysia's air force chief Rodzali Daud gave no further details on which direction the Boeing 777-200 flying from Kuala Lumpur to Beijing went or how far it veered off course before disappearing early Saturday.
He said military and civilian radar indicated the aircraft may have made a turn back.
Meanwhile, Reuters said that officials investigating the plane were narrowing the focus of their inquiries on the possibility that it disintegrated mid-flight.
A massive international sea search has turned up no trace of the jet, though Vietnamese authorities said late Sunday a low-flying plane had spotted a rectangular object in waters about 90 kilometers south of Tho Chu island, the same area where oil slicks were spotted earlier.
State media speculated the object might be from the missing plane.
Also Sunday, Thai police said they were investigating a "passport ring" as details emerged of bookings for the flight made in Thailand with stolen European passports.
Two Europeans - Christian Kozel, an Austrian, and Luigi Maraldi of Italy - were listed on the passenger manifest of flight MH370, but neither man boarded the plane.
Both had their passports stolen in Thailand during the past two years. Malaysia has launched a terror probe investigating the suspect passengers and the United States has sent in the FBI to assist.
Malaysian Transport Minister Hishammuddin Hussein said authorities are investigating the identities of two additional passengers who boarded the plane with suspicious papers.
Interpol said Sunday no country had checked the international police agency's database that held information about the stolen Austrian and Italian passports used to board the Malaysia Airlines flight.
The Malaysia Airlines flight disappeared from radar screens about an hour after taking off from Kuala Lumpur for Beijing in good weather. Most of the passengers were Chinese.
Air traffic controllers say they never received a distress calls before the jet disappeared.
The Boeing 777-200 is a very popular plane with an excellent safety record.
The most recent accident involving a Boeing 777 was the Asiana Airlines crash at San Francisco International Airport in July 2013. Three people were killed. Pilot error is suspected in that incident.