SEOUL, South Korea - Chinese students clashed with anti-Beijing demonstrators at the Olympic torch relay Sunday in Seoul, throwing rocks and punches at the latest troubled stop on the flame's round-the-world journey.

Thousands of police guarded the torch from protesters blasting China's treatment of North Korean refugees. Nonetheless, a North Korean defector tried to set himself on fire to halt the relay.

The small groups of anti-torch demonstrators were far outnumbered by seas of red-clad Chinese supporters waving red national flags, who took to the streets of the South Korean capital to defend the torch.

Police deployed 8,000 officers, some running beside the flame while others rode horses and bicycles with the relay through the 1988 Olympics' host city.

On other legs of the torch relay, it was China's crackdown on violent protests against Chinese rule in Tibet that triggered attempts to disrupt the run heralding the August games. But in South Korea, many critics focused on Beijing's treatment of defectors who try to escape their lives of hardship in the North.

Thousands of North Koreans have fled across the loosely controlled Chinese border and many remain in hiding in China. If caught, they are deported by Chinese authorities and face likely imprisonment in life-threatening conditions back in the North.

The man who tried to immolate himself, 45-year-old Son Jong Hoon, had led an unsuccessful public campaign to save his brother from execution in the North, where he was accused of spying after the two met secretly in China. About an hour into the relay, Son poured gasoline on himself in the middle of a street, but police quickly surrounded him and carried him away before he could set himself alight.

Two other demonstrators tried to storm the torch to interrupt the relay but failed to hinder its 24-kilometer (15-mile) trip from Olympic Park _ built in honor of the 1988 Summer Games _ to City Hall.

Police said five people, including a Chinese student, were arrested.

Scuffles broke out near the relay start between a group of 500 Chinese supporters and about 50 demonstrators criticizing Beijing's policies. The demonstrators carried a banner reading, "Free North Korean refugees in China." The students threw stones and water bottles as some 2,500 police tried to keep the two sides apart.

One Chinese student swatted at the demonstrators with a flagpole. Another student was arrested for allegedly throwing rocks, said an official at a police station near Olympic Park. The official asked not to be named because the probe was under way.

"The Olympics are not a political issue," said Sun Cheng, 22, a Chinese student studying the Korean language in Seoul. "I can't understand why the Korean activist groups are protesting human rights or other diplomatic issues."

Thousands of Chinese paced the torch on the 4 1/2-hour-long relay, some chanting, "Go China, go Olympics!"

Before the relay, two South Koreans who had been chosen to run said they would boycott it to protest China's actions in Tibet.

The torch arrived in Seoul from Japan, where Chinese supporters also outnumbered protesters who failed to disrupt the run.

After Seoul, the torch was scheduled to make its first-ever trip to North Korea for a relay Monday. Disruptions were not expected in the North, an authoritarian state that tolerates no dissent.

Officials from North Korea's Olympic Committee, the Pyongyang city vice mayor, and the Chinese ambassador to Pyongyang were at the airport early Monday to greet the torch's arrival, broadcaster APTN reported. A 12.4-mile (20-kilometer) relay will take place in the streets of Pyongyang on Monday.