BEIJING - Police and security officials displayed a show of force here and in other Chinese cities Sunday, trying to snuff out any hint of protests modeled on the uprisings in the Middle East and North Africa. In Shanghai, several hundred people trying to gather were dispersed with a water truck.

Premier Wen Jiabao, meanwhile, used a morning Internet chat to promise to purge senior officials who are corrupt and to rein in inflation and rising home prices, directly addressing some of the most common grievances of ordinary Chinese.

Since a January uprising in Tunisia spurred similar anti-government protests across the Arab world, threatening long-entrenched authoritarian regimes, China's Communist rulers have reacted nervously, with both defensive and aggressive tactics.

Officials have used state-run media outlets to dismiss any comparisons of those regimes with China. At the same time, they have stepped up public comments on the need to address "social conflict" and to tackle problems such as the growing income disparity between the rich and poor. They also have detained a number of activists and human rights lawyers and blocked Internet search terms considered sensitive, such as "Egypt," "Tunisia" and even U.S. Ambassador Jon Huntsman Jr.'s Chinese name. And they have issued warnings to foreign journalists to be mindful of reporting restrictions.

A previously unknown group has used an overseas-based Chinese-language Web site to call for a series of peaceful, silent protests - named "jasmine rallies" after the Tunisian uprising - on consecutive Sunday afternoons in cities across China. The rallies were called for heavily trafficked commercial areas, public squares and parks, ostensibly so silent protesters could blend in with ordinary passersby to avoid arrest.

However, police on Sunday were out in huge numbers in Beijing, Shanghai and other cities at the sites where the rallies were supposed to take place. Blue-uniformed police officers and security volunteers with red armbands lined the streets in Beijing's Wangfujing area. The bustling commercial street, with a McDonald's and a Gap store, is close to the Forbidden City and Tiananmen Square, the site where hundreds of Chinese pro-democracy demonstrators were killed in 1989 when tanks rolled in to quash a six-week student-led protest. On Sunday, policemen patrolled with German shepherds and a water truck normally used for street cleaning traversed back and forth.

Police in Beijing stopped some foreigners and asked for identification, turning away journalists from entering the area. At 2:30 p.m., about a half-hour after the scheduled start of the silent protest walk, officers blocked off the entrance to Wangfujing Street with police tape. The unusually heavy police presence attracted curious onlookers, who snapped pictures with cellphone cameras. At Wangfujing, a foreign journalist shooting video for a news agency was reportedly punched and kicked in the face by plainclothes Chinese security officers who confiscated his camera. The Foreign Correspondents Club of China reported that more than a dozen other journalists were roughed up at the site.

At the Peace Cinema in Shanghai, opposite the People's Square near the city's main municipal building, a few hundred people tried to gather. Policemen used whistles and loudspeakers to keep the crowd moving, and police converged whenever a group of more than a dozen people appeared to be forming. A street-cleaning vehicle spraying bursts of water also kept crowds at bay.

Some people in Shanghai said they heard about the "jasmine rally" and came to see if there would be any public speaker. Some openly complained about government corruption and the need for an opening of the system.

"I came here today to see how people protest against the government, which is corrupt and rules in an authoritarian way," said a 71-year-old man who asked that only his family name, Cao, be used. "Democracy is the trend in the world. No country in the world can be an exception to the process."

Another man, named Xia, 64, said that there were 400 to 500 people gathering at People's Square when he arrived around 1 p.m. but that they were dispersed by the spray from the water truck. He said he would keep returning to try to protest because he was already in his 60s and not afraid.

"Ordinary Chinese people have no power, and we can only express requests through gatherings like this," Xia said. "When there are more people gathering, these will become a serious warning to the government."

Premier Wen sat for two hours for an Internet chat, with the Xinhua News Agency and the central government's Web site, addressing common complaints and answering questions submitted online. It was Wen's third such chat, coming just before the March opening of the National People's Congress, China's nominal legislature.

During the session, Wen discussed the problem of corruption, following the recent firing for "discipline violations" of Liu Zhijun, the minister of railways and the top official in charge of China's rapidly expanding high-speed-rail development.

Wen said investigating and targeting top officials involved in corruption would be a "primary task" for 2011, and he said some government officials had grown too powerful, with too few checks on their authority.

"The main leaders in our government have too much power," he said. "Power is too concentrated."

richburgk@washpost.com Researcher Wang Juan in Shanghai contributed to this report.