From New York Times

In the latest sign of efforts to prevent dissent during the Beijing Olympics, political activists in Shanghai say they have been warned against expressing their opinions, speaking with foreigners or visiting Beijing until after the Games.

The activists, who have petitioned the city government over grievances in the past, say they were summoned by the police, or detained and issued warnings against making political statements before or during the Games.

The warning against dissent in Shanghai appears to be part of a broader national effort to avert protest by Chinese, particularly those known as petitioners, meaning those who seek the redress of grievances that run the gamut from land use and environmental problems to corruption and political matters. One Shanghai petitioner said that he and others were detained on June 18 after a memorial service for an activist who died shortly after being released from prison last year.

“We were taken to a place and kept there for half a day,” said the petitioner, Xu Zhengqing. “Finally a policeman from our neighborhood came along and read a notice that said, ‘Don’t go to Beijing during the time of the Olympics.’ I asked to keep the notice, but they refused.”

In recent weeks, the government has also blocked Web sites on topics like discrimination complaints by Chinese carriers of hepatitis and anti-Japanese protests involving claims of Chinese ownership of the Diaoyu Islands, which are also claimed by Tokyo.

Beijing is making its final preparations for the Olympics, which open on Aug. 8. In another security measure, anti-aircraft missile batteries were recently installed around the capital’s new National Stadium, which is known as the Bird’s Nest.

China has also tightened access to visas for foreigners and has stepped up surveillance of its borders as part of a heightened terrorism alert.

Officials of the Shanghai Public Security Bureau declined to confirm or deny reports of the warnings to activists.

Cui Fufang, an activist who was detained, said that she was told by the police that if she ignored the warning and traveled to Beijing she would be detained for 5 days for a first infraction, and 10 days if she went to the capital a second time. “I challenged them, asking if I was a citizen or not,” Ms. Cui said. “When they answered ‘yes,’ I asked, ‘Why can’t a citizen go of her own free will to our nation’s capital?’ They said it was because I was a petitioner, and petitioners make trouble.”

Chang Xiongfa, another Shanghai-based activist, said he had been warned by the police that if he and his associates did not cooperate, “we would be dealt with.”

“They said they were carrying out a political assignment and needed our cooperation,” Mr. Chang said. “I told them, ‘Wasn’t it our own government that said the Olympics have nothing to do with politics?’ ”

In Chengdu, the capital of Sichuan Province, which was recently struck by a major earthquake, a local education bureau warned schools to be on the lookout for troublemakers.

“Schools must set up an effective plan to ensure stability,” read the bureau’s notice, which called for 24-hour surveillance to “absolutely prevent petitioners from going to Beijing.”

In Lishui City, in Zhejiang Province, local officials and the police were ordered not to take vacations from July to September. “Their aim must be zero petitions to the provincial and national government,” a notice online read.

In many localities the authorities have repeated the motto “early report, early control, early solve,” urging people to prevent protests of any kind.

“Local governments are doing everything they can in order to stop petitioners,” said Li Jianqiang, a human rights lawyer in Qingdao. “Every unit, factory and school has been ordered to keep an eye on people who might try to make their way to Beijing.”