SAN FRANCISCO — A band of American leftists is denouncing the Olympics-related protests against China as a plot to undermine Beijing’s Communist government and divert attention from the American-led war in Iraq.

“We’re here because we’re opposed to the United States’s attempts to colonize China,” a member of the Party for Socialism and Liberation, Paul Greenberg of San Francisco, said. “They’re trying to break off Tibet from China in order to allow the U.S. to occupy it. … Tibet has been part of China since before any Western countries even existed.”

A small band of demonstrators from the left-wing group gathered on the outskirts of the pro-China, Olympics-sponsored celebration on San Francisco’s waterfront. The group, hoisting a banner reading “Say No to the U.S.-CIA Campaign Against China,” was less well-received when it turned up at a pro-Tibet rally and candlelight vigil Tuesday night.

More than two dozen activists signed a statement posted on the Internet this week warning of a “demonization campaign” seeking to use the Olympics to pressure on China about Tibet and the violence in Sudan’s Darfur region. “These U.S. actions constitute an attempt to destabilize and dismember the People’s Republic of China,” the statement, signed by an attorney general under President Johnson, Ramsey Clark, and a former president of the National Lawyers’ Guild, C. Peter Erlinder, among others, said.

At the Tibetan rally Tuesday, the group defending China was rebuked by one of the most left-wing members of the left-leaning San Francisco Board of Supervisors, Chris Daly.

“There are some war protesters up the way who say we shouldn’t be calling for self-determination in Tibet. But they can’t have it both ways. They can’t say ‘U.S. troops out of Iraq, self-determination for the Iraqi people’ but ‘It’s okay for China to oppress Tibetans.’ That is not consistent,” Mr. Daly said. Mr. Daly called the Iraq war illegal, but Mr. Greenberg insisted the Tibetan spiritual leader in exile in India, the Dalai Lama, is “playing a role like that” of the Iraqi exile who encouraged an American invasion of Iraq, Ahmad Chalabi. The Dalai Lama has not publicly endorsed any invasion or any violence at all in Tibet. In addition, he has never supported calls for Tibetan independence and has publicly sought only autonomy for his homeland.

“That’s what he says now,” Mr. Greenberg said dismissively.