(BEIJING) -- The internationally acclaimed and controversial Chinese artist Ai Weiwei has been missing since Sunday morning after being detained while going through immigration at the airport in Beijing.
Authorities separated him from staff he was travelling with and turned off his cell phone.
Shortly after Ai was detained, 40 police officers arrived at his studio and raided it, confiscating dozens of items and taking away eight of his assistants.
A Twitter message sent from his office said, "There are police at the front and back doors, no way to go in or out."
Ai's staff members were released a few hours later, but no one has heard from Ai Weiwei.
If he remains in custody, this will be the most high-profile detention yet in a government crackdown in which dozens of dissidents and activists have been swept up. All mention of Ai's arrest has been deleted from Chinese websites. And Beijing police officials have not commented.
Ai's assistant, who was travelling to Hong Kong with Ai when he was taken into custody, told the BBC, "I went back to check with the security officers and they said, 'He has other business. You go on the flight on your own.'"
The arrests appear to be related to the government's concern over an online call for a "jasmine revolution." Some of those detained have been charged with "inciting subversion of state power," the same charged Nobel Peace Prize winner Liu Xiaobo faced. He is serving an 11 year prison sentence. Ai Weiwei was blocked from leaving China in December ahead of the Nobel Peace Prize ceremony in Oslo.
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