Ai Weiwei, China’s best-known contemporary artist, is under investigation for ‘economic crimes,’ according to the Chinese government.

Police detained him at Beijing airport last week and raided his art studio north of the capital city.

An outspoken critic of the government, Ai Weiwei’s informal arrest comes during the pinnacle of a widespread crackdown on activists and dissidents in China. With 23 already detained, three formally arrested, and over a dozen missing, some human rights activists are calling this the worst silencing in over 10 years.

Having experienced similar harassment from police in the past, Ai appeared to be relatively protected by the status of his late father, a famous poet, and his international profile as a seasoned artist. Ai designed the Olympic ‘Bird’s Nest’ stadium and the ‘Sunflower Seeds’ instalment at the Tate Modern last year.

Ai told CNN last year, “They crack down on everybody who has different opinions – not even different opinions, just different attitudes.

“Simply to have different opinions can cost (dissidents) their life; they can be put in jail, can be silenced and can disappear.”

A ministry spokesman told reporters during a briefing that the 53-year-old artist’s detainment “has nothing to do with human rights or freedom of expression.”

He refused to comment on the nature of the ‘economic crimes’ that Ai was reportedly arrested for, but added that other countries should respect China’s laws.

Ai has not been seen since officers detained him at immigration in Beijing Airtport while on his way to a business trip. Airline assistants were told that the artist had “other business” and was prohibited from boarding the aircraft.

Nearly twenty plain-clothes officers searched his Caochangdi studio and shut off power throughout the surrounding neighbourhood. One officer seized the mobile of a Guardian journalist who was taking a photograph of the scene and deleted the image saying, “You are not allowed to be on this street, you must leave.”

Officials continued to search the studio three times this week, claiming they wanted to check that Ai’s staff, particularly the foreign workers, were registered correctly. Ai’s assistant said Ai never had any issues concerning his staff in the past.

Ai’s mobile could not be reached this week and his studio telephones appeared to be switched off. Any and all posts about Ai on the internet were deleted by the government, although many outspoken supporters have taken to using pseudonyms for the artist to avoid censorship.

Just days before his detainment, the artist reportedly said, “it’s hard to know what will happen in a few years. I will never leave China behind unless I am forced to – Hopefully that is not going to happen.”