Pro-Tibetan protesters today disturbed a high security ceremony to light the Olympic flame in Greece.

International dignitaries were gathered at Olympia, the site of the ancient Olympics, when three members of the Paris-based Reporters Without Borders ran onto the field to disrupt a speech by Liu Qi, president of the Beijing organising committee and Beijing Communist party secretary.

The demonstrator who got nearest to Liu Qi was carrying a banner showing the Olympic Rings as handcuffs but failed to unfurl it before being arrested.

Police detained the men along with a Tibetan campaigner and a Greek photographer travelling with him in the nearby village of Olympia, just outside the site of the ancient Games.

Lhadon Tethong, director of Students for a Free Tibet, said the men were taken to the local police station. "One of our colleagues saw them being dragged by about 20 police through town," she said.

"If the Olympic flame is sacred, human rights are even more so," Reporters Without Borders said in a statement. "We cannot let the Chinese government seize the Olympic flame, a symbol of peace, without denouncing the dramatic situation of human rights in the country."

When the incident took place, Chinese state TV cut away to a pre-recorded scene, preventing Chinese viewers from seeing the protest. TV commentators on Chinese TV did not mention the incident.

After the arrest of the men the ceremony went ahead smoothly. Actor Maria Nafpliotou, dressed as a high priestess, used a concave mirror to catch the sun's rays and light the Olympic flame.

International Olympic committee president Jacques Rogge attended the ceremony and said afterwards: "It's always sad when there are protests. But they were not violent and I think that's the important thing."

Once lit, Nafpliotou handed the torch to Alexandros Nikolaidis, who won a silver medal in taekwondo at the 2004 Athens Games but the progress of the flame was hindered by protestors along its route.

Several pro-Tibet demonstrators, including a Tibetan woman whose body had been painted red, lay down on the road in the athelete's path.

A total 645 torchbearers will carry the flame for a week over 950 miles through Greece. It will make a stopover at the Acropolis before being handed over to Chinese officials at the Athens stadium where the first modern Olympics were held in 1896.

The flame will travel 85,000 miles across five continents to reach the Olympic stadium in Beijing on August 8.

Demonstrations continued today in countries neighbouring Tibet. In northeast India, police stopped nearly 500 Tibetan exiles from marching to the Chinese border to demand a halt to China's crackdown on protesters in Tibet.

Police blocked their entry into the state of Sikkim that borders China, said an officer, Sonam Bhutia. The protesters carried Tibetan flags and chanted slogans demanding they be allowed to go to Tibet.

"We have barricaded the road and we shall not allow the Tibetans to continue the march," Bhutia told the Associated Press.

The Tibetans living in India's northeast began their march on Thursday from the state of West Bengal and planned to enter China using the Nathu La pass in Sikkim.

"The goal of the marchers is to fight shoulder to shoulder with Tibetans inside Tibet," said Ugyen Tsewang, general secretary of the Northeast Tibetan Youth Congress, which organized the march.

"We haven't given up our effort yet. We are persuading the state authorities to allow us continue our march," Tsewang said by phone from Rongpo, a town in West Bengal state.

"We will start a hunger strike if the state authorities don't accept our demand," he said.

"We want to confront the Chinese police and not the Indian police."

Protests started on March 10 in the Tibetan capital of Lhasa on the 49th anniversary of a failed uprising against Chinese rule.

They turned violent four days later, touching off demonstrations among Tibetans in three neighbouring Chinese provinces.

Beijing's official death toll from the protests is 22, but the Tibetan government-in-exile in India has said 99 Tibetans have been killed.

India has generally allowed the Tibetan exiles to protest peacefully, but earlier this month detained several dozen protesters who had planned a separate march from northern India to Tibet to coincide with the opening of the Beijing Olympics, saying India would not tolerate actions that embarrassed China.

· This article was amended on Tuesday March 25 2008. In the article above we originally referred to Lhadon Tethong as a man. This has been corrected.

· This article was amended on Wednesday March 26 2008. In the article above we said that a convex mirror was used to light the olympic flame. This should have been a concave mirror. This has been corrected.