BEIJING — Chen He Nan is an exceedingly rare creature in China: a dyed-in-the-wool rabble-rouser, a charismatic political activist capable of bringing thousands of people onto the streets in noisy, even violent, protest.

Yesterday, Chen's voice was still raspy from his weekend success, in which he urged on at least 10,000 people in a frenzied anti-Japan demonstration. Some in the throng defied police, while others marched on the Japanese Embassy and ambassador's residence, where they threw stones and broke windows.

This was an extraordinary event because China's authoritarian government tolerates no dissent and typically breaks up street protests as soon as they materialize. Yet every once in a while the government indulges the passions of an inflamed public.

This is where Chen came in, with a megaphone, leading the protesters as police calmly watched without intervening.

Chen, a 20-year-old college student, confirmed he had government backing for the protest, which called for a boycott of Japanese goods and fed off a longstanding antipathy toward Japan for not atoning properly for the atrocities it committed in China before and during World War II.

Chen said that he was in touch with organizers in other cities, where similar large protests occurred over the weekend. A crowd of 10,000 chanting anti-Japanese slogans gathered Sunday in Shenzhen. Earlier in the day, another 10,000 demonstrators surrounded the Japanese consulate in Guangzhou.

This is significant because it reaffirms the potential for mass demonstrations in China, 15 years after the Tiananmen massacre. Those protests, which began with an innocent memorial service for an ex-leader, quickly spread into a nationwide pro-democracy movement that threatened to topple the government. In the end, troops raided the square and killed hundreds of people, if not more.

With China privatizing its economy but refusing to open its political system, there is always the possibility that aggrieved people — from the unemployed to democratic activists to persecuted Christians — could mount a challenge to government control. Communist Party officials say the risk of "social unrest" presents the greatest threat to the country.

In the case of Saturday's demonstrations, it appears the government quickly lost its nerve. All traces of the event have been censored. There was no mention of the incidents in Sunday's or yesterday's state-controlled media, and Web sites and chat rooms have been blocked.

For the government, the anti-Japanese sentiment is worth supporting because it feeds a growing sense of nationalism in China, which the Communist Party considers crucial for maintaining its legitimacy. The party stakes its claim to power on their World War II guerrilla war against Japanese invaders. Critics say the party manipulates anti-Japanese sentiment to divert attention from anger at corruption, economic problems and a lack of democracy.

The underlying cause of the protests is widely regarded to be a growing fear in China that rival Japan may become a permanent member of the U.N. Security Council, should U.N. reform proposals be adopted in September. Japan is the second-largest contributor to the United Nations after the U.S., and has allied itself with Germany, India and Brazil, the other rising regional powers, in pushing for permanent status on the world body's inner council. The U.S. recently began openly backing Japan's longstanding bid for a seat.

That brought a swift response from China. An Internet petition against the move, for example, held partly on the official Xinhua news Web site, got 25 million signatures.

While China may regard the demonstrations as part of a larger strategy to thwart Japan's U.N. bid, the outbursts play into a deepening apprehension in Japan over its vulnerability in a region with a nuclear North Korea and a more powerful China.

China won't say whether it will oppose a permanent Security Council seat for Japan, which carries with it power to veto U.N. actions. But as the only Asian nation among the current five permanent members, China is unlikely to want to give up that exclusive status and boost its rival's influence in the world body.

The immediate cause of the protest was the decision by Japan's Education Ministry last week to approve the publication of textbooks that whitewash some of the Japanese military's transgressions and overlook other controversies.

"The Japanese brought terrible damage on China and committed a lot of crimes against the Chinese and Asian people, just like the Germans did to the Jewish people," Chen said. "The difference is the Germans could admit the mistakes they made. The Japanese didn't apologize and tried to cover up the truth, even hiding it from their own people. This is something we should never forgive."

Yesterday, Japan called on China to protect Japanese citizens in China and appealed for an end to the violence. Nearly 80,000 Japanese live in China, up by a third in the past year alone.

The countries are bound together by tens of billions of dollars in trade, aid and investment, but political relations are often strained and never warm. China surpassed the United States this year as Japan's top trading partner.

Surging Chinese growth and influence has come at a time of mounting unease over Japan's diplomatic and military ambitions.

Prime Minister Junichiro Koizumi and other politicians have added to tensions by visiting the Yasukuni Shrine, a memorial to war dead including convicted war criminals. This year, China commemorates the 60th anniversary of the end of World War II, a date that is likely to cause renewed Japan-bashing.

More recently, competing claims to territory in the East China Sea and China's exploration for gas under the sea floor near Okinawa have aggravated tensions. Last year, a Chinese submarine entered Japanese waters. Tokyo demanded and said it received an apology.

Another issue is Japan's recent pledge to help the U.S. defend Taiwan in the event of an attack by Beijing.

The protest Saturday was the biggest in Beijing since 1999, when the U.S. Embassy was besieged after NATO warplanes bombed the Chinese Embassy in Belgrade during the war over Kosovo.

Thousands of Chinese protesters marched through the Chinese capital, shouting slogans and throwing rocks, bottles and eggs at the Japanese Embassy. One group burned a Japanese flag.

"China's economy needs to grow even bigger so Japan won't be able to push us around ever again," said protester Huang Liyi, a 22-year-old chemist at the protest.

Additional information from The Associated Press and The Christian Science Monitor