The pilot who crashed his small plane into Beijing's tallest skyscraper last week was suffering from "chronic insomnia and anxiety" and did so for "personal reasons", authorities said Thursday.

The crash had killed the pilot, officially identified only by his surname Liu, and wounded 13 others.

Liu, a 66-year-old Beijing resident, was a divorced freelancer who lived alone, the Chaoyang district government said in a statement, adding Liu's diary contained "multiple expressions of ending his life".

"The comprehensive investigation concluded that this was a case of endangering public safety caused by personal reasons," the statement said.

One of the injured has been discharged from the hospital, officials said.

Videos of the crash at the CITIC Tower had been widely circulated on social media before being scrubbed off the Chinese internet, as authorities investigated what many observers viewed as a huge security breach.

The 109-storey CITIC Tower, also known as China Zun, is located just a few kilometres from Zhongnanhai, the Communist Party's headquarters.

The building has long been treated by many locals as a lucky charm. But shortly after the crash last Friday, even unrelated photos and memes of the skyscraper were taken down from Chinese social media platforms.

In the days after the crash, at least three aviation firms told the BBC that they had been told to suspend light aircraft operations.

On the afternoon of the crash, Liu had taken off from an airport in Pinggu district and conducted both accompanying and solo flights, the Chaoyang government's statement said.

"During his solo flight, he deviated from the designated area and lost contact with the airport, subsequently colliding with the high-rise building and dying at the scene," the statement said.

According to authorities, Liu had obtained his sport pilot's licence in 2021 and his private pilot's licence in 2024.

The plane he flew last week was a two-seat, single-engine Aurora SA60L manufactured by Chinese company Sunward Aircraft, according to flight tracking service Flightradar24.

At 6.9m long, with a wingspan of 8.6m, it is designed for touring, aerial photography and recreational aviation.