Hong Kong's oldest university launched an overnight operation Thursday to dismantle a statue commemorating those killed in Beijing's Tiananmen Square in the latest blow to academic freedoms as China cracks down.

The eight-metre (26-feet) high "Pillar of Shame" by Jens Galschiot has sat on the University of Hong Kong's (HKU) campus since 1997, the year the former British colony was handed back to China.

The sculpture features 50 anguished faces and tortured bodies piled on one another and commemorates democracy protesters killed by Chinese troops around Tiananmen Square in 1989.

Its presence was a vivid illustration of Hong Kong's freedoms compared to the Chinese mainland where the events at Tiananmen are heavily censored.

But Beijing is currently remoulding Hong Kong in its own authoritarian image after democracy protests two years ago and commemorating Tiananmen has become effectively illegal.

In October, HKU officials ordered the removal of the sculpture citing new but unspecified legal risks.

They made good on that promise in the early hours of Thursday morning.

Clanging through the night

University staff used floor-to-ceiling sheets and plastic barriers to shield the statue from view as sounds of drilling and metal clanging could be heard throughout the night, according to an AFP reporter at the scene.

Security guards blocked journalists from getting close and tried to stop media outlets filming.

Workers in hard hats could then be seen using a crane to manoeuvre a large chunk of the sculpture, wrapped in plastic, toward a nearby container.

HKU confirmed the statue had been removed and placed in storage after the operation was completed.

"The decision on the aged statue was based on external legal advice and risk assessment for the best interest of the University," the university said.

Its statement said no party had ever obtained approval to display the statue and also cited the colonial-era Crimes Ordinance in justifying its removal.

That law includes the crime of sedition and has been increasingly deployed by authorities -- alongside a new national security law imposed by Beijing -- to criminalise dissent.

'Shocking'

Galschiot told AFP it was "strange" and "shocking" for the university to make a move on the statue, which he said remains his private property.

"This is a really expensive sculpture. So if they destroy it, then of course we will sue them," he added. "It's not fair."

Galschiot said he had offered to take the statue back and, with the help of lawyers, tried different ways to get in touch with the university.

HKU officials never contacted him or alerted him to the action that began late Wednesday, he said.

The artist sent an email to supporters, encouraging them to "document everything that happens with the sculpture".

"We have done everything we can to tell (HKU) that we would very much like to pick up the sculpture and bring it to Denmark," it said.

Hong Kong used to be the one place in China where mass remembrance of Tiananmen was still tolerated.

For three decades, the city's annual June 4 candlelight vigil would attract tens of thousands.

With its slogans for democracy and ending one-party rule in China it became a symbol for the political freedoms enjoyed by Hong Kong.

But that era is now over.

Authorities have banned the last two vigils citing both the coronavirus pandemic and security fears.

They have charged the leaders of the vigil organisers with subversion -- a national security crime -- and shut down a Tiananmen museum that the group used to run.

Unlawful assembly prosecutions have been brought against dozens of activists who took part in both the 2020 and 2021 banned Tiananmen vigils.

Scores of opposition figures have been jailed or fled overseas, and authorities have also embarked on a mission to rewrite history and make the city more "patriotic".