China's Olympic torch relay ignited more protests on its troubled world tour Friday, sparking demonstrations across this Japanese city despite the mobilization of thousands of riot police.


Dozens of demonstrators waved Tibetan flags protested as the flame arrived, and one self-proclaimed monk was arrested near the starting point of Saturday's relay. Reports said the man had a knife and was carrying a protest statement.
The relay _ making its 16th international stop _ has been disrupted by protests or conducted under extremely heavy security at many sites since it left Greece.
The protests are largely in response to China's crackdown last month on protests in Tibet, which it has governed since the 1950s, and to concerns over human rights issues in China.
The international route ends next week, with stops in South Korea on Sunday, North Korea on Monday and Vietnam on Tuesday. The flame arrives on Chinese soil on May 2 in Hong Kong, for a long journey around the country before the Aug. 8 start of the games.
Japan has taken severe measures to ensure its 11.6-mile relay goes smoothly. Buses full of riot police patrolled the city, while helicopters buzzed in the air.
Five police guards in track suits will surround the runners, and 100 uniformed riot police will trot alongside. The vacant lot where the relay will begin _ a last-minute substitution after a Buddhist temple pulled out _ will be closed to the public, as will be all rest stops along the way.
After arriving in Nagano by bus early Friday, the flame was spirited away to a hotel and put under heavy security. About 3,000 police have been mobilized.
Japanese officials said the security was unavoidable, and called for calm.
"In a festive environment where everyone can celebrate, we hope the Olympic torch relay will proceed smoothly," Chief Cabinet Secretary Nobutaka Machimura said in Tokyo.
But the high-profile police presence has dissipated any festive mood in Nagano, which hosted the 1998 Winter Games.
"I have nothing against the relay itself, it's all the other stuff that is bothersome," said Hirotoshi Mizugami. "It will cause a lot of traffic jams and disrupt things here; they could have just as easily done it in Tokyo where they are better prepared for this sort of thing."
Groups including Amnesty International and Reporters Without Borders have announced plans to protest. About 2,000 Chinese exchange students were expected to show their support.
Zenkoji, the largest Buddhist temple in Nagano, last week declined to host the start of the relay, citing security concerns and sympathy among monks and worshippers for their religious brethren in Tibet. The 1,400-year-old temple also said it would co-host a prayer ritual for Tibet at the start of the relay.
The problems with the torch relay and reports of foiled terrorist plots in China have raised larger concerns of violence during the Beijing Games, the head of Interpol said Friday.
Ronald Noble told an international security conference that potential attacks could involve efforts to block transportation routes, interfere with competitions, assault athletes or destroy property during the Olympics.
In Vietnam, authorities expelled an American citizen of Vietnamese origin who planned to disrupt the relay there, state media reported. Vuong Hoang Minh, 34, was put on a flight to the U.S. on Thursday, the Vietnam News Agency said. It said Minh told authorities he planned to snatch the torch.