- "His current situation is unknown. We have contacted his family and lawyer and legal formalities are being processed," according to a handwritten statement posted to Hua's Twitter account and signed by artists Ji Feng and Guo Zhenming.
Beijing-based artist Hua Yong has been detained by police after documenting the mass eviction of migrant workers from the Chinese capital, his friends said Monday.
"His current situation is unknown. We have contacted his family and lawyer and legal formalities are being processed," according to a handwritten statement posted to Hua's Twitter account and signed by artists Ji Feng and Guo Zhenming.
In the weeks before he disappeared, Hua uploaded dozens of videos on YouTube and Chinese social media platform WeChat documenting the destruction of migrant neighbourhoods on the outskirts of Beijing.
Since setting up a YouTube account only two weeks ago, his videos have been viewed tens of thousands of times and some have been translated by others into English.
Hua was taken from a friend's home in the northern city of Tianjin in the early hours of Saturday after fleeing Beijing to evade police, other friends told AFP.
"Police grabbed him. Didn't you know? Nobody is able to contact him," one of them said on condition of anonymity.
The Tianjin public security bureau could not be reached for comment.
- 'Ruined in an instant' -
Hua's videos, usually shot with a selfie stick, brought viewers into recently demolished migrant neighbourhoods and recorded his conversations with displaced low-income workers.
In one he walks between heaps of rubble, gesturing around him and saying, "The sky is very blue today. But look at what's behind me, all ruined in an instant."
On Friday night Hua posted several videos on his Twitter account entitled, "They're here". In the videos he said police were at the door and he would soon have to leave with them.
"Daddy is using these last minutes to sing you a song, 'Happy birthday to you' ... Daddy wants our country to be better; It should be just, fair, free and democratic with free speech," Hua said, addressing his three-year-old daughter.
Hundreds of millions of migrants who moved from China's countryside to its cities fuelled the country's dramatic economic boom in recent decades.
But some are no longer welcome in overcrowded Beijing, which seeks to cap its population at 23 million by 2020 and demolish 40 million square metres of illegal structures -- mostly shops and homes for migrants -- by the end of the year.
Authorities argue that they need to clear dangerous buildings after a fire killed 19 people last month. A blaze in another migrant area killed five people last week.
Fire safety is a major problem in the city's cheap migrant housing, which often has jerry-rigged electrical wiring and an absence of emergency exits.
But the brutal efficiency of the demolitions and mass evictions has provoked an unusual public outcry that has put officials on edge.
Amnesty International China researcher Patrick Poon said authorities are "very concerned" that discussions about the topic will harm China's image.
President Xi Jinping has led a sweeping crackdown on civil society since taking power in 2012, targeting everyone from human rights lawyers to celebrity gossip bloggers.
In recent years activists have been jailed on charges such as "picking quarrels and provoking trouble", "subversion of state power" and defamation for spreading "false rumours" online.
"Ironically, by targeting Hua Yong, it further hurts China's image when even documenting what happened could be justified as a crime," Poon told AFP.
© Agence France-Presse