The missing Malaysia Airlines Boeing 777-200ER was airborne for a total of five hours, according to sources quoted by the Wall Street Journal.
U.S. investigators now suspect the aircraft stayed airborne for about four hours past the time it reached its last confirmed location, according to the publication's sources.
The WSJ referenced engine data which its sources claim indicates the plane continued to fly for hours beyond its last known location.
A total flight time of five hours could put the flight's final destination at the Indian Ocean, the border of Pakistan or even the Arabian Sea, the WSJ claimed in a tweet.
The report came as Malaysian authorities said they had failed to find any evidence of wreckage at a potential debris site identified by Chinese satellites.
The missing Boeing 777-200ER sent at least two bursts of technical data back to the airline before it disappeared, according to the New Scientist magazine.
The Malaysian Insider previously reported that the data may help investigators understand what went wrong with the aircraft, with no trace of Flight MH370 found since it disappeared early on Saturday morning.
In one of the biggest aviation mysteries in memory, dozens of aircraft and vessels from an array of countries, including the US Navy, have failed to find a shred of evidence pointing to the plane's fate.
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Major General Datuk Affendi Buang briefs the media during an update on the missing Malaysia Airlines plane. Photo: Getty.
"Malaysia Airlines has not revealed if it has learned anything from ACARS data, or if it has any," reported the New Scientist, referring to the Aircraft Communications Addressing and Reporting System (ACARS), which automatically files technical reports during every flight so that engineers can spot problems.
The reports are sent at four stages throughout the flight - during take-off, the climb, at
a point during cruising and on landing - via VHF radio or satellite.
However, in a Malaysia Airlines statement, the airline claimed: "All Malaysia Airlines aircraft are equipped with ACARS which transmits data automatically. Nevertheless, there were no distress calls and no information was relayed."
New Scientist claimed that the maker of the missing jet's Trent 800 engines, Rolls Royce, received two data reports from the now missing flight at its global engine health monitoring centre in Derby, England, where it reportedly keeps real-time monitors on its engines in use.
"One was broadcast as MH370 took off from Kuala Lumpur International Airport, the other during the 777's climb out towards Beijing," it said.
Malaysia probes people-smuggling link as jet search widens
Two suspect men who flew on a missing Malaysian airliner appear to have been Iranian illegal immigrants, officials said Tuesday, lessening fears of terrorism but doing little to unlock the agonising riddle of what has befallen the plane's 239 passengers and crew.
The Malaysian military said they believe they had tracked the missing plane, with primary radar evidence suggesting the plane changed course flew over the Malacca Straits.
A US Navy Seahawk helicopter takes off from the USS Pinckney in the Gulf of Thailand during search efforts. Photo: Reuters.
Local newspaper Berita Harian quoted Malaysian air force chief General Rodzali Daud to say that the plane had been detected hundreds of kilometres away from the initial last contact point, and that a military base had reported detecting the plane at Pulau Perak.
Another unnamed military official said: "It changed course after Kota Bharu and took a lower altitude. It made it into the Malacca Strait."
But Malaysia's air force chief on Wednesday denied reports the jet had been detected far from its planned flight path.
“The (air force) has not ruled out the possibility of an air turn-back on a reciprocal heading before the aircraft vanished from the radar,” General Rodzali Daud said in a statement.
“This resulted in the search and rescue operations being widened to the vicinity of the waters (off the west coast of Malaysia).”
But he denied a Malaysian media report on Tuesday that quoted him as saying that radar had last detected the plane over the Strait of Malacca off western Malaysia.
That location would have indicated that Malaysia Airlines flight MH370 had banked far to the west of its intended flight path over the South China Sea.
Rodzali said he “did not make any such statements” and that Malaysian newspaper Berita Harian published “what is clearly an inaccurate and incorrect report”.
Authorities have said the plane's last known point of contact with air-traffic control was off eastern Malaysia early on Saturday.
On the fourth day of a multinational search at sea and on land, relatives desperate for news of loved ones aboard Malaysia Airlines MH370 said their hopes for a miracle were ebbing away.
Authorities have doubled the search radius to 100 nautical miles (equivalent to 185 kilometres) around the point where the Boeing 777 disappeared from radar over the South China Sea early Saturday, en route from Kuala Lumpur to Beijing.
"We are intensifying our search and rescue, and hoping against hope there is still an opportunity for us to rescue (those on board)," Malaysian Transport Minister Hishammuddin Hussein told reporters.
The 34-year-old son of Malaysian security guard Subramaniam Gurusamy was on the flight to do business in Beijing for an oil company.
"My three-year-old grandson is asking: 'where is Dad?' We tell him father has gone to buy sweets for you," Gurusamy, 60, said as he broke down in tears.
"Please bring back my son. I am praying for divine intervention. That is the only hope we have."
Students in China pray for the passengers from the missing Malaysia Airlines plane. Photo: Twitter.
Malaysia had opened a terror probe, joined by FBI agents from the United States. But the revelation of the identities of two men who boarded the flight using stolen European passports suggested they were young Iranian migrants seeking a new life overseas.
Interpol named the pair as Pouri Nour Mohammadi, 18, who was booked to fly on to Germany, and Delavar Seyed Mohammad Reza, 29, who was ticketed through to Denmark.
Reza's ultimate destination was Sweden, where he intended to apply for political asylum, according to Swedish newspaper Aftonbladet.
The two travelled to Kuala Lumpur from Doha on their real Iranian passports, and their identification was helped by relatives in Europe who reported them missing, officials said.
"It is part of a human-smuggling issue and not a part of a terrorist issue," Interpol chief Ronald Noble told reporters in France, adding that the international agency was more and more "certain that these individuals are probably not terrorists".
- People-smuggling ring? -
Iran offered its assistance to the Malaysian investigation, pledging to provide "any information on the Iranians and their status as soon as it is available".
Police in Southeast Asia agreed that people-smuggling was emerging as the likeliest explanation for the identity fraud.
The two passports -- one Italian and one Austrian -- were stolen over the past two years in Thailand, where police have long been battling a thriving trade in Western documents used by criminal gangs.
"We believe that these two passports were stolen by a human-smuggling gang who send people to work in third countries, especially European countries," Lieutenant General Panya Maman, commander of Thailand's southern police region, told AFP.
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Malaysia's national police chief Khalid Abu Bakar said his officers were not ruling anything out but were now focusing on theories including a hijacking, sabotage or psychological problems among passengers or crew.
Elsewhere on the judicial front, French prosecutors on Tuesday opened an investigation for manslaughter following the plane's mystery disappearance.
The move does not indicate any evidence of foul play necessarily, but is standard practice since four of the missing passengers are French nationals, and allows French magistrates to take a more active part in the investigation.
Flight MH370, captained by a veteran pilot, had relayed no indications of distress, and weather at the time was said to be good.
The vastness of the search zone reflects authorities' bafflement over the plane's disappearance. The operation has grown to involve 42 ships and 35 aircraft from Southeast Asian countries, Australia, China, New Zealand and the United States.
- 'Emotional breakdown' -
The plane's last confirmed radar sighting was off Vietnam's southern coast. "In terms of our assessments and predictions ? we have little hope of a positive outcome," Pham Quy Tieu, Vietnamese deputy minister of transport, said.
The search sphere now includes land on the Malaysian peninsula itself, the waters off its west coast, and an area to the north of the Indonesian island of Sumatra.
That covers an area far removed from the scheduled route of flight MH370, which officials say may have inexplicably turned back towards Kuala Lumpur.
China, which had 153 of its nationals on board the plane, said it would harness 10 satellites equipped with high-resolution imaging to help in the search. Boeing said it was joining a US government team to try to unravel the mystery of what happened to its 777-200 plane.
Conflicting information has deepened the anguish of relatives, with tests on oil slicks in the South China Sea showing they were not from the missing jet and reports of possible debris from the flight also proving to be false alarms.
At a hotel in Beijing where relatives are gathered, a man in his 20s surnamed Su said: "I hope it is a hijacking, then there will be some hope that my young cousin has survived.
"My uncle and aunt had an emotional breakdown, they are not eating, drinking and sleeping."
A total of 17 Chinese relatives have so far taken up an offer from Malaysia Airlines to fly to Kuala Lumpur to be closer to the operation, and more are expected in the coming days, the airline said.
Chinese foreign ministry spokesman Qin Gang reiterated demands for Malaysia to look after the relatives "and give them accurate information in a timely fashion".
Malaysia Airlines stressed: "We are as anxious as the families to know the status of their loved ones."