The Chinese army has warned of possible legal action after images of detained artist Ai Weiwei were projected onto its Hong Kong headquarters, DPA reported.
The People's Liberation Army said the stunt breached Hong Kong law, even though city police said no offence had been committed, the South China Morning Post reported.
The reaction came after images of the artist detained since trying to board a flight from Beijing to Hong Kong on April 3 were beamed by protesters onto landmark buildings in the city at night.
Images up to 10 metres high were beamed onto buildings including the headquarters and barracks in Hong Kong's Central district with the slogan "Who's afraid of Ai Weiwei?"
The army statement quoted by the Post said its headquarters were "not usual public areas but military restricted zones or protected areas according to Hong Kong law."
"No one can paint or project pictures or images onto the outer wall of the barracks without the garrison's permission."
China has thousands of soldiers stationed in the former British colony since it reverted to Chinese rule in 1997. They keep a low profile and rarely venture out.
The Chinese government says Ai Weiwei is being held for alleged economic crimes. He has not been charged with any offence.