By JIM YARDLEY
   Published: July 2, 2008
   

   BEIJING — Two United States representatives who were in Beijing to lobby for the release of more than 700 political prisoners had hoped to have dinner on Sunday with a group of Chinese human rights lawyers. But security agents had a different idea: they detained some of the lawyers and warned the others to stay away.
   
   Teng Biao, an activist lawyer, shown in 2007. He was placed under house arrest Sunday.
   The detention is the latest example of how Chinese security agents are increasing pressure on dissidents in advance of the Beijing Olympics in August. The governing Communist Party has issued broader orders for local governments to defuse public protests, as a violent demonstration involving an estimated 30,000 people erupted last weekend in southwestern China.
   
   In Beijing, a spokesman for the Foreign Ministry said the representatives, Frank R. Wolf of Virginia and Christopher H. Smith of New Jersey, both Republicans, had overstepped their visas in arranging to meet the lawyers. The legislators, both sharp critics of China, expressed outrage over the interference by security agents.
   
   “The people we were supposed to have dinner with all got stopped,” Mr. Smith said in a telephone interview on Tuesday afternoon. “All of the world is watching, and this kind of behavior doesn’t bring anything but more scrutiny to their human rights abuses.”
   
   Mr. Wolf called on President Bush to boycott the Olympic opening ceremonies if the detained lawyers were not released and if there were “no progress” on releasing 734 political prisoners on a list that the two representatives presented to the Chinese.
   
   Mr. Bush has been invited to the opening ceremonies by President Hu Jintao and has rejected calls that he not attend.
   
   On Tuesday afternoon, Liu Jianchao, the Foreign Ministry spokesman, said the two legislators should not have tried to meet with the lawyers. “They should not intervene in China’s internal affairs or conduct something that is harmful to China-U.S. relations,” he said during a regular news briefing.
   
   Asked if visiting representatives must get approval from the Chinese government to meet with private citizens, Mr. Liu said: “The two congressmen applied to come to China to get in touch with the United States Consulate. We hope the two U.S. congressmen can respect the country they visit and obey Chinese laws. Regarding the issues on religion and human rights, the exchange between the two countries is more meaningful than meeting private citizens.”
   
   The representatives said they came to Beijing to discuss human rights, religious freedom, the Olympics and Darfur. Mr. Smith said they met Monday with the former foreign minister, Li Zhaoxing, and gave him their list of political prisoners. “He took it and said they would look at it,” Mr. Smith said. “Our argument is that these people have done nothing wrong.”
   
   The guest list at the Sunday night dinner was supposed to include three activist lawyers, Li Baiguang, Teng Biao and Li Heping. They were among this year’s winners of the Democracy Award by the National Endowment of Democracy in Washington. Li Baiguang and Li Heping have met with Mr. Bush.
   
   On Sunday afternoon, authorities took Li Baiguang to a Beijing suburb, where he was placed under house arrest, said Chinese Human Rights Defenders, an advocacy group. Mr. Teng, who was also detained this year, was taken to the same Beijing suburb but later returned to his apartment under house arrest.
   
   Another well-known lawyer, Jiang Tianyong, was blocked from leaving his apartment by two Beijing police officers, the advocacy group said. Still another lawyer, Li Fangping, said three police officers were stationed outside his apartment and threatened to follow him wherever he went.
   
   The two representatives did manage to meet with a Chinese pastor, Zhang Mingxuan, but Mr. Smith said security agents placed the pastor under house arrest afterward.
   
   China is making broader efforts to increase security and curb public protests ahead of the Olympics. On June 8, the central government held a video conference to begin a national campaign in the name of preserving harmony for the Olympics to prevent petition campaigns by disgruntled citizens and to stop demonstrations and other “mass incidents.”
   
   Local demonstrations have become common in China, especially in rural areas where peasants protest illegal land seizures and corruption. But authorities, concerned about a potentially embarrassing spectacle during the Games, are calling on local officials to solve problems and prevent petitioners from coming to Beijing.
   
   The potential for unexpected protests was illustrated over the weekend when thousands of people burned government buildings in the county of Weng’an in Guizhou Province in the southwest. China Daily, the official English-language newspaper, reported that 30,000 people participated in a “mass action” after a smaller group protested against possible police malfeasance in handling a case that involved the death of a local teenage girl.
   
   Family members of the girl believe that she was killed by relatives of local officials. The riot erupted after the police ruled her death a drowning and cleared the officials’ relatives. Rioters burned government buildings and smashed police cars. Paramilitary police officers have since been dispatched to the county to restore order. The controversy has become so large that state media announced on Tuesday that the death of the teenage girl would be re-examined by a team of investigators.
   
   Zhang Jing contributed research.