Search planes found no sign on Thursday of a missing Malaysia Airlines aircraft in an area where satellite images had shown debris, taking the as-yet-fruitless hunt into a sixth day.
Adding to the deepening mystery surrounding the fate of Flight MH370 and 239 people on board, The Wall Street Journal reported on Thursday that U.S. investigators suspect the aircraft flew for about four hours after reaching its last confirmed location under conditions that remain murky.
But Malaysian authorities quickly dismissed the report. "As Malaysia Airlines will confirm shortly, those reports are inaccurate," said Transport Minister Hishammuddin Hussein.
On Thursday, Vietnamese and Malaysian planes scanned waters where a Chinese government agency website said that a satellite had photographed three "suspicious floating objects." The location was close to where Flight MH370 lost contact with air traffic control, but the searchers were unable to detect any objects, said a Reuters journalist, who was aboard one of the search planes.
One U.S. official close to the investigation said the Chinese satellite report was a "red herring," according to Reuters.
Malaysia's civil aviation chief, Azharuddin Abdul Rahman, told reporters in Kuala Lumpur on Thursday that the latest search for debris proved little. "There is nothing," he said. "We went there, there is nothing."
The Wall Street Journal report said U.S. investigators based their suspicion that the flight had continued after losing contact on an "analysis of signals sent through the plane's satellite-communications link designed to automatically transmit the status of onboard systems," attributing the news to unnamed sources.
U.S. counterterrorism officials are examining the possibility that the transponders were turned off by the pilot or somebody else on board the plane to avoid radar detection while the jet was diverted to an undisclosed location, according to the newspaper.
It is unclear, the paper reported, if the investigation is gathering evidence pointing to espionage or terrorism.
The Malaysian military may have traced the missing jetliner to an area south of the Thai island of Phuket, hundreds of miles to the west of its last known position, the country's air force chief, Rodzali Daud, said Wednesday.
His statement followed a series of conflicting accounts of the flight path of Flight MH370, a Boeing 777-200ER that vanished on March 8. The discrepancies left authorities uncertain about where to search for the plane.
The last definitive sighting of the aircraft on civilian radar screens came shortly before 1:30 a.m. on Saturday — less than an hour after the plane took off from Kuala Lumpur — as it flew northeast across the mouth of the Gulf of Thailand bound for Beijing.
What happened next remains baffling, and the differing accounts put out by various Malaysian officials have drawn criticism of their handling of the crisis.
On Wednesday, Rodzali told a news conference that an aircraft was plotted on military radar at 2:15 a.m., 200 miles northwest of Penang Island off Malaysia's west coast.
But there has been no confirmation that the unidentified plane was Flight MH370, he said, adding that Malaysia was sharing the data with international civilian and military authorities, including those from the United States.
"We are corroborating this," he said. "We are still working with the experts."
Malaysian officials, under fire over the long and unsuccessful hunt for signs of the plane, defended their handling of the search on Wednesday — but they acknowledged that they are still unsure which direction the aircraft was headed in when it vanished, highlighting the massive task facing the international search.
Amid intensifying confusion and occasionally contradictory statements, the country's civil aviation authorities and military said Flight MH370 may have turned back from its last known position between Malaysia and Vietnam, possibly as far as the Strait of Malacca, a busy shipping lane off Malaysia's western coast.
Government officials said they have asked India to help search near the Andaman Sea, suggesting they think the jetliner might have reached those waters after crossing into the Strait of Malacca, some 250 miles from the flight's last known coordinates.
How the aircraft might have done this without being clearly detected by radar remains a mystery, raising questions over whether its electrical systems, including transponders allowing it to be spotted, were either knocked out or turned off. If it did manage to fly on, that would challenge earlier theories that the plane may have suffered a catastrophic incident, initially thought reasonable because it did not send out any distress signals.
The search area has been expanded to almost 27,000 nautical square miles (an area roughly equivalent to the state of Indiana), authorities said, adding that 43 ships and 40 aircraft from eight nations have been deployed. Hishammuddin, the transport minister, described the multinational search as unprecedented.
Al Jazeera and wire services