SAN FRANCISCO - Security was tightened on the Golden Gate Bridge and elsewhere around the city Tuesday as officials prepared for massive protests of China’s crackdown in Tibet during the Olympic torch’s only North American stop on its journey to Beijing.

The Olympic flame was whisked to a secret location shortly after its pre-dawn arrival Tuesday following widespread and chaotic demonstrations during the torch relay in London and Paris. Activists are protesting China’s human rights record, its grip on Tibet and support for Sudan despite years of bloodshed in Darfur.

The flame is scheduled to be paraded through the city Wednesday on a six-mile route that hugs San Francisco Bay. Already, one runner who planned to carry the flame dropped out because of safety concerns, officials said.

It began its 85,000-mile journey from Ancient Olympia in Greece to Beijing on March 24, and was the focus of protests from the very start.

Hours after it arrived in San Francisco, protesters marched to the Chinese Consulate, calling on China to cease its heavy-handed rule of Tibet.

Meanwhile, a few miles away in Chinatown, leaders of China’s expatriate community held a news conference calling for a peaceful relay, and said they were proud China was selected to host the summer games.

In Beijing, International Olympic Committee President Jacques Rogge said the body’s executive board would discuss Friday whether to end the international leg of the torch relay because of the demonstrations. He said he was “deeply saddened” by the previous protests and was concerned about the relay in San Francisco.

“We recognize the right for people to protest and express their views, but it should be nonviolent. We are very sad for all the athletes and the people who expected so much from the run and have been spoiled of their joy,” Rogge said.

Hundreds of activists carrying Tibetan flags and wearing traditional clothes gathered in United Nations Plaza, a pedestrian area near San Francisco’s City Hall, to denounce China’s policy toward Tibet and the recent crackdown on protesters there. They then marched to the Chinese Consulate as part of a daylong Tibetan Torch Relay.

“This is not about us battling the torchbearers,” Lhadom Tethong, executive director of Students for a Free Tibet, told the crowd outside the consulate. “This is about the Chinese government using the torch for political purposes. And we’re going to use it right back.”

San Francisco was chosen to host the relay in part because of its large Asian population.

David Lee, executive director of the Chinese American Voters Education Committee and a professor of political science at San Francisco State University, said while many Chinese agree with critics of China, on the whole, Chinese-Americans feel a tremendous sense of pride that the Beijing Olympics chose San Francisco as the only relay site in North America.

At a news conference Tuesday, businessowners asked for calm.

“We are begging for five hours of peace,” said Sam Ng, president of the Chinese Six Companies, a prominent benevolent association.

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Some residents also expressed dismay at the protests.

Ling Li, 29, who immigrated from China’s Guangdong Province eight years ago, said she was disappointed that this pivotal moment in her country’s history was being marred by demonstrations. She believes that Tibet is a rightful part of China and its quest for independence should not be part of the Olympics.

“If I support the Olympics, of course I don’t support the protests. This is the first time China has had the Olympics. We should be proud of this,” she said.

Pro-Tibet activists and other human rights groups said they’d encouraged their supporters to protest peacefully and not disrupt the relay or the torch runners.

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“We can be effective without (disruption),” said Allyn Brooks-LaSure, a spokesman for Save Darfur. “Disrupting tomorrow’s ceremonies couldn’t possibly embarrass Beijing any more than their disastrous Darfur policy already has.”

Still, law enforcement agencies prepared for the worst. Mayor Gavin Newsom said the city reserved the right to adjust the flame’s route if necessary.

The Fire Department will have ambulances along the torch’s route, the San Francisco Sheriff’s Department will have 50 or more extra deputies on patrol, and vans will be available to haul away arrested protesters.

“We are trying to accomplish two goals here. One is to protect the right to free speech and the other is to ensure public safety, and here in San Francisco we are good at both of those things,” said Newsom spokesman Nathan Ballard.

The FAA has restricted flights over the city to media helicopters, medical emergency carriers and law enforcement helicopters and airplanes, such as those the California Highway Patrol will use to monitor the torch’s route.

The CHP has also increased the number of officers on the ground, to guarantee the flow of traffic, protect the bridges that connect the San Francisco Bay Area and provide immediate help to police.

“The first and foremost concern is security,” said San Francisco Olympic Torch Relay Committee spokesman David Perry. “Security for those who will carry the torch and security for those who, of course, are also exercising their First Amendment right to protest.”

Perry said one of the torchbearers, who hasn’t been identified, had pulled out of the relay over safety concerns.

Newsom said there was a strong likelihood the relay’s route would be changed. He said the ultimate decision would be made by Police Chief Heather Fong.

The six-mile path currently assigned for the relay is shorter than the courses in Paris and London, making it easier to secure. Newsom said the amount of time set aside for the relay’s opening and closing ceremonies already had been cut, but he would not elaborate.

Security was tightened on the Golden Gate Bridge on Tuesday. On Monday, three protesters scaled the famed span and tied the Tibetan flag and two banners to its cables. Pedestrians and bike riders now must have any large bags checked before they are allowed to cross the bridge.

After San Francisco, the torch is scheduled to travel to Buenos Aires, Argentina, and then to a dozen other countries. The relay also is expected to face demonstrations in New Delhi and possibly elsewhere on its 21-stop, six-continent tour before arriving in mainland China May 4. The Olympics begin on Aug. 8.

The round-the-world trip is the longest in Olympic history, and is meant to highlight China’s rising economic and political power.