Possible debris from missing Malaysian airplane spotted by Vietnamese Navy

A Vietnamese Navy search plane has spotted an object suspected of belonging to a Malaysian jetliner that vanished from radar screens and went missing more than 24 hours ago, according to the Civil Aviation Authority of Vietnam. An unknown source said preliminary investigations are narrowing on the possibility of mid-air disintegration, Reuters reported.

Earlier Sunday, Malaysia Airlines said it was "fearing the worst" for its plane carrying 239 people, as the government said it was investigating four passengers who may have held false identity documents.

There were no reports of bad weather and no sign of why the Boeing 777-200ER would have fallen off radar screens about an hour after it took off from Kuala Lumpur for Beijing. The Malaysian military said the missing flight turned back before disappearing, according to a radar report.

"We are not ruling out any possibilities," Malaysia Airlines CEO Ahmad Jauhari Yahya told a news conference. The country's transport minister said Sunday the search area has been expanded due to possibility the missing aircraft turned back.

Malaysian investigators are checking the identity of four passengers on a missing Malaysia Airlines flight, but have not yet determined if the plane was downed by an attack, Hishamuddin Hussein, who is also defense minister, added.

"All the four names are with me," he told reporters.

He confirmed that Malaysian investigators had met counterparts from the FBI, and said the investigation was focusing on the entire passenger manifest. Interpol said it was of "great concern" passengers were able to board the international flight with passports registered in a lost or stolen database, which hadn't been consulted prior to boarding, Reuters reported.