The latest leg of the Olympic torch relay is well under way in South Korea with protesters vowing to disrupt its run through the capital Seoul.
The 24-km (15-mile) route from Olympic Park to City Hall is heavily guarded by 8,000 police officers.
Human rights groups have said thousands are preparing to protest over China's forced repatriation of North Korean refugees and its crackdown in Tibet.
Police have warned anyone trying to disrupt the relay would be severely punished.
The US embassy has cautioned its citizens in Seoul to avoid unnecessary travel during the relay, which started shortly after 1400 local time (0600 BST).
Dozens of human rights activists took part in a demonstration near the Olympic Park on Saturday ahead of the torch's arrival.
In addition to protests against the Chinese occupation of Tibet, the relay is also seen as an opportunity to raise the issue of China's policy of repatriating North Korean defectors.
Vowing to stop the march, human rights lawyer Kim Sang-chul told South Korean news agency Yonhap China had repatriated 75,000 North Koreans over the past 15 years.
"China tries to promote itself as a civilised nation but what it's doing to the defectors is uncivilised," he said.
Security for the relay includes 120 police runners and a helicopter.
"Those who attempt to stop the relay will surely be arrested on the site and given stern punishment," a police spokesman said.
Over the following few days, the torch will stop in North Korea and Vietnam.