Liu Li knew he might not be able to get to see the blind barefoot lawyer Chen Guangcheng on Sunday. After all, Mr. Chen, a persistent thorn in the Chinese government’s side, has been under heavily guarded house arrest for more than a year. But Mr. Liu did not expect to return on crutches from his attempted visit.

“About seven or eight men rushed up to me, kicked me to the ground, stole my cellphone, smashed my ankle and knocked me out,” Liu recalled Tuesday. “And the police did nothing when I reported what had happened.”

Liu was one of a group of around 40 activists who were attacked and beaten by more than 100 thugs on Sunday afternoon outside the village of Dongshigu in the eastern province of Shandong where Chen has been illegally locked up in his house with his family since being released from jail in September last year.

“I did not think the situation was so dark,” said Liu. “There is no law in that area.”

The violence marked the second weekend in a row that unidentified thugs have violently broken up efforts by human rights activists and ordinary citizens to visit Chen in a burgeoning campaign to win his freedom.

“Though it is extremely costly for the activists, [the campaign] is bringing a lot of attention to Chen’s case and there are chances that it could ultimately succeed if the pressure continues,” suggests Nicolas Bequelin, a China analyst with Human Rights Watch.

Chen has been under round-the-clock guard in his home village since being released at the end of a 51-month jail sentence he had incurred on charges of disrupting traffic. Human rights activists say the real reason he was imprisoned was his vigorous defense of women who had been forcibly sterilized in abuses of China’s one child policy.

Instead of being freed, Chen was put under house arrest with his wife and daughter, and forbidden to contact the outside world. Local and foreign activists doing their best to monitor his situation say they fear he has been regularly beaten.

Foreign journalists and European diplomats are among those who have been violently turned back when they have tried to visit Chen, and in recent weeks a growing number of courageous Chinese activists have risked being beaten up or detained trying to reach his house.

“He was a pioneer” of China’s rights movement, said Peng Zhonglin, who helps petitioners bring their complaints to official attention, explaining why he was among the group that was attacked on Sunday. “We are simply citizens making an effort to try to improve the judicial system.”

“We wanted a peaceful atmosphere,” he added, “so we were all carrying Chinese flags.” But no sooner had the group set foot on the bridge that marks the entrance to Dongshigu village than “more than 100 people, mostly men in their 20’s, emerged from the woods and ditches on the other side of the bridge, rushed at us and beat us with their fists and with rocks. It seemed as though they had been lying in wait for us.”

Most of the 37 activists escaped relatively unharmed, Mr. Peng said, but five were seriously injured and three of them were detained by the police and have not been heard from since.

“It was legal for us to visit Chen,” he insisted, “we were beaten illegally but the local and central governments ignore this crime. It’s impossible that the authorities do not know what is happening.”

Though the Chinese government has in the past denied to protesting foreign diplomats that nothing was amiss in Chen’s case, “activists are exposing this falsehood,” says Mr. Bequelin. “The more incidents like this happen, the more unsustainable it becomes for Beijing to pretend that Chen is free.”