SAN FRANCISCO — Thousands protesting policies of the Chinese government forced officials to sharply curtail the relay of the Olympic torch yesterday on its only visit to America in advance of the Summer Games in Beijing in August.

City officials entirely abandoned the announced torch route past the Ferry Building and Fisherman’s Wharf along San Francisco’s picturesque waterfront. Instead, after a tightly controlled opening ceremony near AT&T Park, the torch disappeared inside a warehouse. It emerged aboard a bus driven to a street a couple of miles from the publicly disclosed route. While thousands of protesters, pro-China demonstrators, and ordinary Americans eager to catch a glimpse of the torch waited in vain halfway across the city, office workers and shoppers were startled to see the torch and the huge coterie of security personnel surrounding it.

The greatly abbreviated route meant the roughly 80 torchbearers had to double up for each leg, and most got to carry the Olympic symbol for only a block or so.

As word spread about the diversion, a game of cat and mouse broke out as hordes of protesters set out to intercept the torch. Some succeeded, jeering as it passed. However, there were no incidents like those seen earlier this week in London and Paris, where demonstrators broke through police lines, lunging at the torch and forcing it to be extinguished.

The last-minute changes angered not only protesters, but also the large pro-China crowd that was entertained by lion dancers, tai chi practitioners, and a marching band as they waited for a torch that never arrived.

“It is unfortunate. It is almost a once in a lifetime to see the torch passing for the Beijing Olympic Games,” a member of a pro-Beijing group that roamed the waterfront looking for the torch, Jiang Yang of San Jose, Calif., said. “We came here to show our voice. I don’t think it was heard in London or in Paris. I think it deserves to be heard.”

Some city officials complained bitterly that the wholesale change to the torch route meant San Francisco residents had been deceived by their mayor.

“Gavin Newsom runs San Francisco the way the premier of China runs his country — secrecy, lies, misinformation, lack of transparency, and manipulating the populace,” the president of the city’s Board of Supervisors, Aaron Peskin, told the San Francisco Chronicle. “He misled supporters and opponents of the run. People brought their families and their children,” Mr. Peskin said, calling the rerouting “a cynical plan to please the Bush State Department and the Chinese government because of the incredible influence of money.”

Mr. Newsom responded that the changes were intended to ensure the safety of all involved.

When the torch was on the streets, it was flanked by a phalanx of local police on motorcycles, as well as by a second line of local police on foot. The torch was also guarded by a group of Chinese paramilitary police wearing light blue tracksuits.

The largest number of protesters were those objecting to China’s recent crackdown in Tibet and plans to run the torch through Tibet to Mount Everest. In an act of guerilla theater, some demonstrators dressed as members of the Chinese military drove a cardboard tank into another group dressed as Buddhist monks.

Some clashes took place as supporters of China tried to block signs held by pro-Tibet and human rights demonstrators who mingled into the pro-China crowd.

“I was accosted by China supporters who hit me with flags. They beat me,” Ed Roecker, 51, of El Cerrito, Calif., said as he held a sign reading “China & USA Hands Off Tibet, Darfur, Palestine, Iraq, Iran … One World.”

As observers from the American Civil Liberties Union loomed, park rangers and police urged him and others to leave the pro-China rally and join other protesters in a park a few hundred yards away.

“This is a provocation,” one park ranger said. “You’re one here among 10,000 people.”

“Is this the area that’s been purchased by the Olympic multinational corporations?” Mr. Roecker replied.

“I think sports and the political should be separated. Sport is sport,” a postdoctoral student from China, Yan Liu, said as she waved American and Chinese flags nearby.

The efforts by law enforcement to escort the demonstrators away agitated some bystanders.

“This is not Communist China!” one man bellowed repeatedly at the top of his lungs as police tried to shift the protesters out of the plaza. He declined to give his name.

City officials used two rows of six-foot-high chain link fences as well as a bevy of portable toilets to separate the pro-China crowd from one of the main areas occupied by anti-China protesters.

Another large contingent of protesters called attention to China’s economic and political relationship with Sudan’s government, which is widely viewed as responsible for an ongoing genocide in that country’s Darfur region.

“I lost a lot of my students, my family members, my relatives,” a former Darfur resident who fled in 2002 and now lives in Philadelphia, Muhdy Bahradin, said. “This isn’t political. … This is about human beings. We have to save human beings.”

“This is a key moment for those of us who have been organizing against this genocide for years,” the president of the American Jewish World Service, Ruth Messinger, said as the Darfur protesters mustered. “The theme of the Oylmpics is ‘One Dream for the World.’ That can’t occur when people in Darfur are being displaced at the rate of tens of thousands a week.”

Ms. Messinger said her group will launch a campaign next week to encourage Jews celebrating Passover to include a prayer for Darfur in their Seder ritual.

One roving Darfur protest came from a van driven by two Vermont men known for their ice cream and their support of liberal causes, Ben Cohen and Jerry Greenfield. “It’s a ‘China Torch of Disgrace’ modeled on the actual Olympic torch,” Mr. Cohen said as he showed off the decorated metal tube, complete with gas flame, attached to the back of the black van. “The red clouds on the Olympic torch are replaced with black clouds of terror,” he said. The Darfur torch also showed refugees being shot at and terrorized by militiamen on horseback.

“I think it’s the right message to send to China,” Mr. Cohen said. “The Chinese are trying to use the Olympics to tell the world they’ve arrived. … What we are saying back to them is that along with being a big nation comes responsibility.” The Tibet and Darfur protesters called on President Bush to boycott the Olympics opening ceremonies. Leaders from Germany, Poland, and the Czech Republic have announced plans for such a boycott. Prime Minister Brown of England said yesterday that he planned to skip the opening ceremonies, but British officials said he planned to be at the closing gala and that no snub of China was intended.

No cause was too obscure to draw a demonstration yesterday. A small group of Vietnamese carried signs declaring “Paracel and Spratly are Vietnam.” The demonstrators were objecting to China’s occupation of several South China Sea islands claimed by Vietnam.