A "Release Ai WeiWei" sign went up at the top of London's prominent Tate Modern art gallery on Friday in support of the detained Chinese artist and activist.
The gallery put the words in large capital letters on the lightbox capping the former power station which is situated on the bank of the River Thames.
The Chinese government said Thursday Ai was being investigated for "suspected economic crimes," while his family said he was the innocent victim of a political witchhunt.
His secretive detention has caused an international uproar.
Burly, bearded Ai had a hand in designing the Bird's Nest stadium for the 2008 Beijing Olympics, and has juggled a prominent international art career with colorful campaigns against government censorship and political restrictions, often using the Internet.
Follow us
The artist filled the Tate Modern's cavernous Turbine Hall with over 100 million handmade porcelain sunflower seeds for an installment in 2010.
