The Chinese government has begun a crackdown on outspoken Beijing artist Ai Weiwei, staking out his studios and deleting his blog as well as his remarks on China's version of Twitter.

The well-known artist — who was a design consultant on the giant Olympic Beijing National Stadium, a.k.a. the Bird's Nest — has been critical about the death of schoolchildren in the Sichuan earthquake of May 2008.

He began his own investigation, collecting names of the children who died. He had reached more than 5,000 names before his blog was shut down last month.

Ai says the deaths were a direct result of local officials channelling money into their own pockets from school building funds.

The artist recently told the Art Newspaper that plainclothes police are posted outside his studio every day.

He also described an incident in which strangers visited his mother's house. Ai Weiwei asked them for identification, which they refused to provide. When they also refused to leave the house, the artist called local police.

"Two days later an undercover guy was following me, I asked him, 'Why are you following me?' Another came, and I kicked his car door to get him to report it, but he wouldn't. So I went to the police station to make a complaint," he told the art trade paper.

The artist said he will persevere with his criticisms about the disaster in Sichuan and has launched another blog to republish his previous examinations. He said the server is in the U.S.

"I don't know how long it will last before it is blocked," he said.

Ai has a history of agitating Chinese officials. He was a vocal critic of the Olympics in 2008 and eventually distanced himself from the stadium project.

Ai, who was sent to the countryside during the Cultural Revolution, studied film in Beijing before becoming an avant-garde artist.

His work has been exhibited around the world, including the Venice Biennale.