When dissident Chinese artist Ai Weiwei secretly snapped a picture of himself showing a middle finger in Beijing's Tiananmen Square, he knew it was provocative.

But he never thought that picture would be at the heart of rising censorship fears in Hong Kong 26 years later.

The former British colony's reputation as a cultural gateway to China that is free of Communist Party interference and censorship has diminished over the past year as Beijing moved to silence the city's democracy movement.

Once a place where artists never had to fear a knock on the door from China's police, it is now a city where dissent is being expunged.

Beijing's crackdown following huge and often violent democracy protests nearly two years ago has focused on protest leaders and the pro-democracy opposition.

But it has started to bleed into the art world thanks to a sweeping new security law that criminalises much dissent and an official campaign to ensure only "staunch patriots" run the city.

Watching from his home in Berlin, China's best known modern artist around the world told AFP the arrival of mainland style censorship in Hong Kong is all but guaranteed
Watching from his home in Berlin, China's best known modern artist around the world told AFP the arrival of mainland style censorship in Hong Kong is all but guaranteed AFP / John MACDOUGALL

Watching from his home in Berlin, China's best known modern artist around the world says the arrival of mainland style censorship in Hong Kong is all but guaranteed.

"Any sign of freedom of speech, any sign of free expression can be... declared unlawful or subversive to state power," Ai told AFP by phone.

"That law was applied in mainland China but it is also being applied in Hong Kong, there's no question," the 63-year-old added.

For Hong Kong's art community, all eyes are currently focused on the M+ Museum.

For Hong Kong's art community, all eyes are currently focused on the M+ Museum, a 60,000 square-metre venue set to open later this year
For Hong Kong's art community, all eyes are currently focused on the M+ Museum, a 60,000 square-metre venue set to open later this year AFP / Peter PARKS

A 60,000 square-metre venue set to open later this year, it boasts perhaps the finest collection of contemporary Chinese art in the world thanks in part to a massive donation by Swiss collector Uli Sigg.

The museum's online catalogue lists 249 works by Ai Weiwei alone. It also has photographs by Liu Heung-shing of Beijing's deadly 1989 crackdown in Tiananmen, an event scrubbed by censors on the mainland.

But there are question marks over whether it can display its more provocative pieces given the precarious new legal and political atmosphere in Hong Kong.

Pro-Beijing politicians there have already accused the museum of breaking the new security law and "spreading hatred against the country" with their collection, singling out Ai's Tiananmen picture.

On Monday, a government official confirmed Ai's photo would not be displayed when the museum opens and he said he would welcome national security police to vet its collection for any possible breaches.

Ai described the curators behind M+ as "very professional" people with "creative integrity" who are dealing with "an extremely fast-changing world".

Pro-Beijing politicians have accused the museum (bottom L), which lists 249 works by Ai Weiwei alone, of "spreading hatred" against China
Pro-Beijing politicians have accused the museum (bottom L), which lists 249 works by Ai Weiwei alone, of "spreading hatred" against China AFP / Peter PARKS

But he said he now wonders whether any of his work will be displayed, including two large installations that are meant to be included in the opening.

"Hong Kong's more liberal, more democratic society, is disappearing," he lamented.

Ai was once feted by Chinese authorities and helped design Beijing's Bird's Nest Olympic stadium.

But he found himself on the receiving end of the state's wrath, especially when he criticised authorities over their handling of 2008 Sichuan earthquake, in which more than 87,000 people died.

He was detained for 81 days in 2011 and eventually left for Germany four years later.

The fact that his photo in Tiananmen Square is triggering Chinese authorities once more is something he welcomes.

"I cannot refuse that feeling of being proud," he mused.

Ai took the picture back in 1995 and it kicked off a series now known as "Study of Perspective".

Wherever Ai went in the world he would take a similar photograph with a middle finger extended, usually towards something politically powerful or culturally important.

He has done it in more than 100 locations, including outside the White House, Germany's Reichstag and Russia's Kremlin.

The fact that Chinese authorities remain so outraged by his Tiananmen gesture is, he says, exactly the point.

"An individual's little gesture can become a state matter and can really shake the foundations of authoritarianism," he said.

Ai was critical of western museums doing deals on the mainland.

He singled out recent collaborations by France's Centre Pompidou and Britain's Tate Modern.

"So many cultural institutions rush to China but do they care about the most important meaning in art which is freedom of expression?" he said.

"Are they going to stay silent seeing professional museums like M+ under unthinkable pressure from the same government they are trying to please," he added.

"Can they show their middle finger?"