Artists and supporters of Ai Weiwei assembled in London over the weekend to protest the continued detention of the Chinese activist and contemporary artist.

Protesters climbed into the Tate Modern's display of Ai's Sunflower Seeds installation on Saturday and scattered posters bearing the message: "Free Ai Weiwei."

The exhibit of 136 tonnes of individually moulded, fired and hand-painted porcelain sunflower seeds has been on display in the Tate's Turbine Hall since October. Though Ai originally intended for visitors to walk on and interact with the exhibit, the contemporary art gallery was forced to cordon it off because of "the potential health hazard from a dust cloud" being raised by enthusiastic visitors.

Outside the Tate, protesters encouraged passersby to read from a list naming 50 Chinese artists, journalists, bloggers and government critics detained by the Chinese government amid a recent crackdown.

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A protester in a rabbit costume to symbolize the Chinese year of the rabbit takes part in a protest calling for the release of Chinese artist Ai Weiwei outside London's Tate Modern on Saturday. (Carl Court/AFP/Getty Images)

A protester dressed as a white rabbit (to represent the year of the rabbit in the Chinese zodiac) carried a banner reading "Ai Weiwei is an artist, not a criminal" and posed with tourists strolling near the riverside gallery.

"There is a movement across the world this spring, whether it is in China or the Middle East, which is about speaking truth to power, and I think Ai Weiwei has become a symbol of that," the British artist known as Bob and Roberta Smith told the Guardian newspaper.

"It is great that people have come here to join in."

Government officials, artists and international human rights groups have called for China to release Ai, who was detained at Beijing airport while attempting to board a flight to Hong Kong on April 3. Authorities also subsequently detained and interrogated the outspoken artist's wife, assistants, friends, family members and associates.

China's Foreign Ministry said Thursday that Ai was being investigated for unspecified "economic crimes" and that his detention had "nothing to do with human rights or freedom of expression."