ATHENS, Greece — Demonstrators disrupted the lighting of the Olympic torch in Greece yesterday, heralding a summer of protest aimed at the most controversial games in two decades.

As the elaborate ceremony to light the flame from the rays of the sun began at Olympia, the site of the ancient games, three French protesters from the Reporters Without Borders organization ran on to the grass where speeches were being given.

One man managed to reach the side of a member of the Chinese politburo and president of the Beijing Olympic Organization Committee, Liu Qi, as he was giving his address. Before police managed to pull him away, he waved a banner saying: “Boycott the country that tramples on human rights.”

He was arrested along with two other protesters, one of whom had tried to grab the microphone shouting “Freedom, freedom.”

As the second torch-bearer, a Chinese swimmer, ran out of the historic stadium and on to public roads, two Tibetans painted in red to denote blood fell on to the road in front of her. More Tibetans were arrested along the roadside, including a pair who unfurled a Tibetan flag saying “Light the Passion Share the Dream: Free Tibet 2008” from a balcony overlooking the route.

“Light the Passion, Share the Dream” is the official slogan of the 2008 torch relay.

Recent unrest in Tibet has forced both the International Olympic Committee and the Chinese government on to the defensive. The president of the International Olympic Committee, Jacques Rogge, insisted before the ceremony that there was no “momentum” for a boycott of the games. “The major political leaders don’t want a boycott,” he said. “There is no momentum for a boycott.”

He also said he was involved in “silent diplomacy” on a range of issues. In his own speech, immediately before Mr. Liu’s, he said the games would be an opportunity for China and the world “to learn, discover, and respect each other.”