SHANGHAI -- U.S. House Speaker Nancy Pelosi, long a fierce critic of Beijing, toured China's financial capital on Monday on a visit focused on environmental issues rather than human rights, though her presence emboldened protesters. 

Pelosi took a low-key approach as she prepared for meetings in Beijing just days ahead of the 20th anniversary of the 1989 crackdown on the Tiananmen Square democracy protests. 

The apparent shift dovetails with President Barack Obama's new emphasis on engagement with Beijing, rather than confrontation over its human rights record. Visits by Pelosi and other senior U.S. figures have been aimed at highlighting cooperation between the two countries on a slew of issues.  

Still, the leading Democratic lawmaker's reputation as a strong human rights defender galvanized petitioners in Beijing, where several hundreds gathered Monday morning near the capital's South Railway Station to air their grievances. Dozens of police stood guard and most protesters were kept behind police lines. 

While many complaints were about individual cases, photos posted on the Chinese-language Web site Boxun.com, a U.S.-hosted Web site banned in China, showed one group of demonstrators holding up a black-and-white cloth banner that said: "Welcome Pelosi. Pay close attention to human rights. SOS." 

Speaking to U.S. business figures Monday in Shanghai, Pelosi noted her commitment to human rights issues over the years. 

During a 1991 visit to Beijing, the Democrat from California unfurled a banner that read "To those who died for democracy in China" in the square. Years later, she attempted to present human rights petitions to then-visiting President Hu Jintao. When Tibetans staged protests against Chinese rule last year, Pelosi visited their exiled spiritual leader, the Dalai Lama. 

"I will continue to speak out for human rights in China and around the world," Pelosi told members of the American Chamber of Commerce in Shanghai. 

"Indeed, protecting the environment is a human rights issue," she said according to a copy of the speech distributed to journalists. "We hope to send a clear message that transparency, accountability, enforcement, and respect for the rule of law are essential if we are to protect our planet," she added. 

Pelosi did castigate North Korea after Pyongyang announced that it had successfully carried out an underground nuclear test, weeks after threatening to restart its rogue atomic program. 

"If today's announcement is true, these tests would be a clear violation of United Nations Security Council Resolution 1718, which requires that North Korea not conduct any further nuclear tests. Such action by North Korea is unacceptable and cause for great alarm," Pelosi said in a written statement. 

Pelosi said she and other members of her delegation planned to urge Chinese leaders to use their influence to get the North to return to six-nation talks aimed at ending its nuclear program. 

The lawmaker arrived over the weekend accompanied by a delegation of four Democrats and one Republican, all members of the House Select Committee on Energy Independence and Global Warming. The main focus of their visit is the shared goal of promoting clean energy and combating climate change. 

Pelosi met Monday with Shanghai Mayor Han Zheng. The two exchanged pleasantries but made no substantive remarks before reporters. The delegation will later meet in Beijing with Hu and other leaders. 

U.S. Senate Foreign Relations Committee chairman and Democrat Sen. John Kerry is also in China, and Treasury Secretary Timothy Geithner will arrive next week. He is expected to reassure Beijing about the strength of the U.S. dollar and thus the value of China's vast holdings of U.S. Treasury notes.