Searchers Report Spotting Plane Debris -

Updated March 9, 2014 9:59 a.m. ET

The fate of Malaysia Airlines flight MH370 is still unknown and the search continues. The WSJ's Jake Maxwell Watts tells us the focus remains in the South China Sea between Malaysia and Vietnam.

KUALA LUMPUR—A Vietnamese search aircraft located fragments Sunday floating in waters off southern Vietnam that are suspected of coming from a Malaysia Airlines3786.KU 0.00%Malaysian Airline System BhdMalaysiaRM0.250.000.00%March 7, 2014 4:56 pm Volume : 18.21MP/E Ratio N/AMarket Cap RM4.18 BillionDividend Yield N/ARev. per Employee N/A03/09/14 Searchers Report Spotting Plan...03/09/14 Countries Put Disputes Aside f...03/09/14 Frustrated Relatives Demand Ac...More quote details and news »3786.KUinYour ValueYour ChangeShort position jetliner that went missing a day earlier with 239 people on board.

The fragments were believed to be a composite inner door and a piece of the tail, Vietnam's ministry of information and communication said in a posting on its website. They were located about 50 miles south-southwest of Tho Chu island.

Officials released photograph of one fragment floating in the water. Malaysia Airlines said it had received no confirmation regarding the suspected debris.

Flight MH370 went missing early Saturday on a flight from Kuala Lumpur, Malaysia, to Beijing and ships and planes scouring the waters had been unable to find it. Vietnam said earlier in the day that a Singaporean aircraft had found a yellow floating object south-southwest of Thu Chu and dispatched ships toward the area. Singapore has declined to comment.

The Vietnamese statement said that the aircraft could not land near the objects to investigate them further because of darkening conditions but would continue the identification process Monday morning.

The disappearance of the flight from Kuala Lumpur to Beijing triggered a search and rescue operation across portions of the Gulf of Thailand and South China Sea, involving the armed forces of several nations, including the United States, Malaysia, Vietnam and China.

The investigation into the fate of the plane has been complicated further by revelations that two passengers appeared to have boarded the plane with stolen passports, prompting airline executives and aviation officials to say that foul play can't be ruled out.

Malaysia's police chief, Inspector-General Khalid Abu Bakar, told reporters in Terengganu on the country's South China Sea coast that while police investigators "don't dismiss the possibility" of terrorism, they weren't considering it the most likely cause for the disappearance of MH370.

Rescuers are looking at the possibility that the plane could have attempted to turn back to Kuala Lumpur, "which could mean that the aircraft could be elsewhere," acting Transport Minister Hishamuddin Hussein, who also serves as Malaysia's defense minister, said at a press briefing.

Military radar readings indicate the plane may have reversed course, the country's air force chief said. Gen. Rodzali Duad said the military is still studying the radar data, and added that it is corroborated by some civilian radar data.

The flight included passengers from more than a dozen nationalities, with just over half of them Chinese. A Malaysian aviation official said at the briefing that the aviation regulator is investigating video recordings of two passengers carrying stolen passports, from check-in to departure. Two people—an Austrian and an Italian—listed as being on the missing jet weren't on the flight. Their passports had been stolen in Thailand.

A 30-year-old Austrian whose name was on the passenger list for the flight wasn't on board. His passport was stolen in Thailand in 2012, an Austrian Foreign Ministry spokesman said.

Another passenger on the list, Luigi Maraldi, an Italian citizen, wasn't on the plane either, Italy's Foreign Ministry said Saturday. Mr. Maraldi's passport was stolen in Thailand a year and a half ago, his father said.

An Austrian and Italian whose names were on the passenger list of flight MH370 but not on the flight both lost their passports in Thailand. The WSJ's Deborah Kan speaks to security consultant Steve Vickers about the thriving trade of selling fake identification in Thailand.

A European security official said it wasn't uncommon for passengers to board flights using stolen passports. In addition, Beijing has emerged as a bustling transit hub in recent years, providing connecting flights to Europe and elsewhere from other parts of Asia, buoyed in part by a 72-hour visa-on-arrival program.

A massive, multinational search and rescue operation to locate flight MH370, meanwhile, continues in the waters between Malaysia and Vietnam.

Until the plane is located, there is little prospect of figuring out what really caused it to vanish. And the longer the search takes, the less likely it is to find any survivors.

At a news conference in Beijing Sunday afternoon, a member of the airline's crisis-management team, said the airline has told family members of passengers to "expect the worst." Ignatius Ong said Malaysia Airlines would make travel arrangements for Chinese family members who wished to fly to Kuala Lumpur to await more news.

Meanwhile, many relatives in Beijing were overcome with grief as they awaited news. Sounds of weeping poured out of rooms of the Metropark Lido Hotel, about 20 minutes from Beijing Capital600008.SH -2.56%Beijing Capital Co. Ltd. AChina: Shanghai¥6.86-0.18-2.56%March 7, 2014 3:04 pm Volume : 11.31MP/E Ratio 27.08Market Cap ¥15.09 BillionDividend Yield 2.19%Rev. per Employee ¥545,232More quote details and news »600008.SHinYour ValueYour ChangeShort position International Airport where the airline had set up a help center for friends and relatives of the passengers. Some of the family members crouched in the stairwells, their cries echoing into the hallways.

Zhang Zhiliang, from Tianjin, and his family huddled in a stairwell in the hotel, crying, "I don't understand." His cousin, 26 and also from Tianjin, was on the flight.


A woman cries in the arrival hall of the International Airport in Beijing, China, on Saturday. Associated Press

Late Saturday, Vietnam reported that one of its search aircraft had spotted two oil slicks some 140 kilometers, or 87 miles, from Vietnam's coast. The slicks could be a sign that the missing plane had crashed, authorities in Hanoi said.

"I can confirm that there was an oil slick, no debris," Mr. Hishamuddin said, adding that Vietnamese authorities are on site to verify whether there is any jet fuel on the sea surface.

On Sunday afternoon, a statement issued in the name of a previously unknown group claimed that the disappearance of the plane was a political act aimed at the Chinese and Malaysian governments and referred to last week's attack in a Chinese train station by alleged Uighur separatists. It stopped short of a claim of responsibility. Malaysian officials said that they were unaware of any claim of responsibility but would investigate all possibilities.

A team of American aviation accident investigators, led by National Transportation Safety Board experts, is en route to Asia to provide assistance regarding the missing jetliner.

China's navy said Sunday that it had sent two warships to help with the search. Beijing had already sent at least one coast guard vessel and two search and rescue ships toward the area, according to state media.

"Once the aircraft location is identified," international accident rules will determine what country will formally lead the probe, the safety board said. The board's announcement is the latest sign of the intense international interest in trying to quickly determine what caused the BoeingBA -0.25%Boeing Co.U.S.: NYSE$128.54-0.32-0.25%March 7, 2014 5:03 pm Volume (Delayed 15m) : 4.20MAFTER HOURS$127.43-1.11-0.86%March 7, 2014 8:59 pm Volume (Delayed 15m): 101,687P/E Ratio 21.30Market Cap $95.56 BillionDividend Yield 2.27%Rev. per Employee $514,38803/09/14 Countries Put Disputes Aside f...03/09/14 Boeing Dreamliner Makes Emerge...03/09/14 Defense Radar Detected Possibl...More quote details and news »BAinYour ValueYour ChangeShort position 777 to disappear from the sky in good weather.

The team, including technical advisers from Boeing Co. and the Federal Aviation Administration, left the U.S. Saturday and would "be positioned to offer U.S. assistance," the board said. The NTSB is unlikely to head up what is bound to be a complex and extensive probe, but the board's expertise is likely to play a big role in establishing the chain of events.

The NTSB's decision, according to air-safety officials, indicates that at least at this point, U.S. aviation regulators and safety watchdogs are treating the plane's disappearance and presumed crash as an accident rather than an act of terrorism.

The officials stressed that could change as more details surface. For now, though, it is the NTSB investigators, rather than law-enforcement or antiterrorism officials, who are leading Washington's public response.

—Vu Trong Khanh, Chuin-Wei Yap, Laurie Burkitt and Celine Fernandez contributed to this article.

Write to Jason Ng at