On Friday afternoon in Shifang, residents at shops and sidewalk cafes described battles that pitted young people against the police in the square around a clock tower in the city’s center. Alerted through the Internet, youths had poured in from neighboring communities in a rare, and new, example of intercity coordination by protesters.

The police initially detained 21 protesters but released them a day later as the crowds swelled. The smelting project itself has been canceled and shows no sign of being restarted, several Shifang residents said, adding that the city had been completely quiet ever since the protests.

Though the Shifang demonstrations appeared to be an isolated example of youth protests on the mainland, young people are heavy users of the Internet in China. And a tone of sarcastic contempt for the authorities is evident in many of their postings, despite censors’ efforts to remove, within hours, any that violate their guidelines.

The protests in Hong Kong, a former British colony returned to China in 1997, have been somewhat similar to the much larger Tiananmen Square protests in Beijing in 1989: large numbers of students have flocked to public spaces in front of government buildings, staging sit-ins and, in some cases, hunger strikes.

Also like the Tiananmen Square protesters, the Hong Kong students have been protesting corruption, particularly a widespread perception here that government officials have become too close to the city’s tycoons by accepting yacht trips while in office and discounted apartments and highly paid jobs after retirement. The Hong Kong protesters have even put up a “goddess of democracy” statue that resembles the Statue of Liberty, similar to the statue used by students during the Tiananmen Square demonstrations.

A rumor spread on Friday that the government had sent provocateurs here to create disturbances that would give the police a pretext to disperse the crowd. The government issued a rare statement to deny the rumor, and Mr. Leung took pains on Saturday to deny it again.

“I asked the police that they must not clear the site,” he said, adding that he had even asked that umbrellas and raincoats be sent out to protesters during a midnight deluge.