Flight data indicates a China Eastern Airlines plane that crashed in March was intentionally put into a nose-dive, according to US media reports.
Investigators have so far not found any mechanical or technical faults with the jet, as per the reports, citing a preliminary assessment by US officials, the BBC said.
The Boeing 737-800 was flying between the southern Chinese cities of Kunming and Guangzhou when it crashed.
All 132 passengers and crew on board the plane died in the crash.
"The plane did what it was told to do by someone in the cockpit," according to the Wall Street Journal, which first reported the story, citing a person familiar with US officials' preliminary assessment of the cause of the crash.
Data from one of the plane's "black box" flight recorders, which was recovered from the crash site, suggested that inputs to the controls pushed the plane into a near-vertical dive, the report said.
ABC News, citing US officials, also reported that the crash was believed to have been caused by an intentional act.
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.