The Boeing 737-800 crashed into a mountainous region in the southwestern Guangxi region on March 21, 2022, in China's deadliest aviation disaster in 28 years.

On the eve of the crash's second anniversary, the Civil Aviation Administration of China (CAAC) issued a seven-paragraph long update of its investigation, saying it had examined the wreckage, checked the flight crew's health status and working conditions at the departure airport.

"The investigation shows that the flight crew and cabin crew of the flight held valid licences and certificates," the CAAC report said. "...and they passed the health check before the flight on that day."

"Before takeoff, no faults or abnormalities were found in the aircraft system, fuselage structure, engines etc.," the CAAC said.

The investigation team will continue to carry out verification and cause analysis and continue to release information on the probe's progress in a timely manner, it added.

Boeing referred Reuters to CAAC for any information on the investigation. China Eastern did not immediately respond to requests for comment.

International Civil Aviation Organization rules require countries probing plane crashes to make a final report publicly available within 12 months or if that is not possible, to publish an interim statement on each anniversary, detailing the progress of the investigation and any safety issues identified.

Last year, the CAAC issued a three-paragraph statement that provided little detailed information and no data from the plane's "black boxes" that would offer clues into its sudden plunge from cruising altitude.

There were internet rumours of a delibrate crash at the time of the incident. The CAAC said at the time such speculation had "gravely misled the public" and "interfered with the accident investigation work".

Chinese officials said in 2022 that a final report into the causes of the crash could take two years or more to complete.

(Reporting by Sophie Yu and Brenda Goh; Editing by Gareth Jones)

By Sophie Yu and Brenda Goh