One of China's best-known dissidents is recovering from brain surgery in Germany after having been assaulted by a Chinese policeman.

Ai Weiwei, an internationally famous artist who helped design the "Bird's Nest" Olympic stadium in Beijing, said in a telephone interview that an operation Monday night at a Munich hospital was successful.

"I am fine, I am definitely in no danger," Mr. Ai said from his hospital bed Thursday.

Ai, an outspoken critic of the Chinese government, was punched in the face by a policeman on Aug. 12, when police broke into his hotel room in Chengdu, the capital of Sichuan Province, in the middle of the night.

He and several other colleagues were then detained for 11 hours, preventing Ai from attending the trial of human rights activist Tan Zuoren, at which he had intended to give evidence.

Mr. Tan had posted comments on the Internet questioning why so many children had died in the 2008 Sichuan earthquake. He was tried for inciting sedition because of his suggestions that shoddy building work was to blame for the large number of schools that collapsed in the quake.

"After the punch, I suffered tremendous headaches all the time," Ai said, but he was too busy preparing for a forthcoming show in Munich to do anything about it. "When I arrived in Germany, I realized I was not functioning well, so I went to a hospital," he said.

Ai had taken special interest in the earthquake's aftermath, compiling a list of names of thousands of victims and posting it on his blog, in the absence of an official count. Access to his blog is blocked in China. (Read the Monitor's report about his efforts here).

Volunteers who helped gather the names for the list were often arrested and expelled from Sichuan. But Ai said at the time he believed that his international renown, and the fact that his father was a highly respected poet, gave him some protection.

He also said that his active use of the Internet made official retribution less likely, because it could be quickly and easily publicized.

"Because of the Internet, we can easily get our voice out," he said in an interview last April. "The faster we can spread our ideas, the safer we are. The more open I am, the safer I am. But maybe that's an illusion."