BEIJING—Chinese authorities detained dozens of political activists after an anonymous online call for people to start a "Jasmine Revolution" in China by protesting in 13 cities—just a day after President Hu Jintao called for tighter Internet controls to help prevent social unrest.
But Chinese authorities seemed to take it seriously, deploying extra police to the planned protest sites, deleting almost all online discussion of the appeal, blocking searches for the word "Jasmine" on micro-blogging and other sites and temporarily disabling mass text-messaging services.
Ahead of the planned protests, more than 100 activists across China were taken away by police, confined to their homes or went missing, according to the Hong Kong-based group Information Center for Human Rights and Democracy.
The online protest appeal is likely to compound the apparent concern among Communist Party leaders that the recent uprisings against authoritarian governments in the Middle East and North Africa could inspire similar unrest in China. The lackluster popular response, however, demonstrates how much harder it would be to organize a sustained protest movement in a country with a well-funded and organized police force, and with the world's most sophisticated Internet censorship system.
At one of the designated protest sites — a McDonald's outlet in Beijing's central Wangfujing shopping district — The Wall Street Journal saw a crowd of several hundred people gather, along with hundreds of uniformed and plainclothes police, shortly before 2 p.m.
The crowd, however, consisted almost entirely of foreign journalists and curious shoppers—many of whom thought there was a celebrity in the area—along with a handful of young people who said they had heard about the protest appeal and come to watch.
The only sign of protest came from a young Chinese man who was detained by police after laying some jasmine flowers outside the McDonald's and trying to take a photograph of them on his mobile phone, witnesses said. At least two other people were detained after altercations with police, but it was not clear whether they were protesting, the witnesses said.
Jon Huntsman, the U.S. ambassador to China—who has been critical of the country's Internet controls—was also in the crowd but quickly left after he was identified by a Chinese crowd member with whom he was chatting.
In Shanghai, meanwhile, police led away three people outside a Starbucks outlet near the planned protest spot after they shouted complaints about the government and high food prices, according to the Associated Press. There were no reports of demonstrations in other cities where people were urged to protest, which included Guangzhou, Tianjin, Wuhan and Chengdu.
The protest appeal had urged people to "take responsibility for the future" and to shout a slogan that encapsulated some of the most pressing social issues in China: "We want food, we want work, we want housing, we want fairness!"
It came at a sensitive time, as China prepares for the March 5 start of the annual meeting of its parliament, the National People's Congress. China's leaders are also anxious to ensure social stability in the run-up to a once-in-a-decade Party leadership change next year, when Mr. Hu and six other top leaders are due to retire.
On Saturday, Mr. Hu summoned national and provincial leaders to a meeting in Beijing at which he called for them to "solve prominent problems which might harm the harmony and stability of the society." Some Chinese and Western analysts have argued that China faces many of the same social problems that have inspired the protests in the Middle East and North Africa, especially rising housing and food prices.
Others, however, say that China is unlikely to suffer similar unrest because living standards are generally rising faster, and social controls are much stronger—especially online. Although an increasing number of people are becoming aware of censorship and ways to circumvent it, Chinese authorities have also been largely successful in controlling the spread of information. Locally operated websites must delete any content the government deems "harmful," and companies that store user information in China must comply if the government requests access to that information.
This has often enabled authorities to quickly identify and stop organized political action before it reaches too many people, all while staying under the radar of most ordinary citizens, who aren't constantly searching for political content. It also makes heavy-handed crackdowns affecting large numbers of Internet users mostly unnecessary.
China blocks websites like Facebook and Twitter, which were used by activists in Egypt, and keeps out other undesirable foreign content, from criticism of China's leaders to information about sensitive historical events, using Web-filtering technology.
President Hu called for even stronger Internet restrictions in his speech on Saturday at the Central Party School in Beijing, which trains rising leaders.
"At present, our country has an important strategic window for development, but is also in a period of magnified social conflicts," he said. Among the steps Beijing had to take, Mr. Hu said, was "further strengthening and improving management of the Internet, improving the standard of management of virtual society, and establishing mechanisms to guide online public opinion."
—Loretta Chao contributed to this article.