According to US media reports, flight data indicates that the China Eastern Airlines plane that crashed in March was deliberately nose-diving.
According to the reports, investigators have not found any mechanical or technical faults with the jet.
During the crash, the Boeing 737-800 was flying between the southern Chinese cities of Kunming and Guangzhou.
The crash killed all 132 passengers and crew.
Wall Street Journal, citing a person familiar with US officials’ preliminary assessment of the crash cause, reported that “the plane did what it was told by someone in the cockpit.”
A black box flight recorder recovered from the crash site indicated that inputs to the controls drove the plane into a near-vertical dive, according to the report.
ABC News, citing US officials, also reported that the crash was believed to have been caused by an intentional act.
Investigators looking into the crash are examining whether it was due to intentional action on the flight deck, with no evidence found of a technical malfunction, according to Reuters, which cited two people briefed on the matter.
China Eastern Airlines previously said the three pilots on board were qualified and in good health.
The airline separately told the Wall Street Journal that there was no indication that any of the pilots was in financial trouble.
The Civil Aviation Administration of China (CAAC), which is leading investigations into the crash, also did not immediately respond to a BBC request for comment.