Analysts say they were smart to change.

“QQ offers no protection from eavesdropping by the Chinese authorities, and it is just as well they stopped using it,” said Rebecca MacKinnon, a China specialist and fellow at the Center for Information Technology Policy at Princeton University. “QQ is not secure. You might as well be sharing your information with the Public Security Bureau.”

But the activists say they are getting around some of those restraints by shifting to different platforms (including a Skype-like network called YY Voice) and using code words to discuss protest gatherings.

For years, labor activists have been exposing the harsh working conditions in Chinese factories by smuggling cellphone images and video out of coastal factories and posting documents showing labor law violations on the Web. New and notable is that these formerly covert activities have become open and pervasive.

Last month, for example, when a string of puzzling suicides was reported at Foxconn Technology near here, one of the world’s largest electronics manufacturers, there were online video postings reportedly showing security guards manhandling workers.

And several people claiming to be Foxconn workers posted their pay stubs online showing that their overtime hours exceeded the legal monthly limit. In Zhongshan, where many of the Honda Lock strikers returned to work at least temporarily on Sunday and Monday while wage negotiations continued, the workers followed a basic model established by those who went on strike last month at a Honda transmission factory in the city of Foshan.

The Foshan strike leaders organized and communicated with more than 600 workers by, among other means, setting up Internet chat rooms on QQ.

“I created one myself the night before the strike, and that had 40 people,” said Xiao Lang, one of the two Honda strike leaders in Foshan. Mr. Xiao was fired by Honda soon after leading the walkout. “We discussed all kinds of things on it,” he said of the QQ chat room, “such as when to meet, when to walk out and how much pay we want.”