BEIJING — Police led away four activists from the U.S. and U.K. today after they unfurled pro-Tibet banners outside Beijing's National Stadium, the site of the Olympic Games' opening ceremony later this week.

Two men from Students for a Free Tibet each climbed an electrical pole in front of the so-called Bird's Nest and put up the banners at dawn, said Lhadon Tethong, the New York-based group's executive director. The other two — a man and a woman — provided support from the base of the poles, she said.

One of the black-and-white banners said "Tibet will be free" and "Tibet Freedom" in Chinese. The other said "One World, One Dream" — the slogan for the Beijing Olympics — followed by "Free Tibet." One of the men also flew the flag of the Dalai Lama's former Tibetan government.

It was the first such demonstration at a venue for the games, which open Friday.

"We've done this action today to highlight the Chinese government's use of the Beijing Olympics as a propaganda tool to whitewash their human rights record on Tibet," protester Iain Thom said from his perch about 50 feet off the ground, according to a recorded cell phone conversation posted on the group's Web site.

The activist group identified the protesters as Thom, 24, of Scotland; Phill Bartell, 34, of Bridgewater, N.J.; Tirian Mink, 32, of Portland, Ore.; and Lucy Marion, 23, of England.

Beijing organizers, who have taken great pains to put in place strict security measures to show that Beijing is capable of hosting the event, condemned the protest.

"We express our strong opposition," said Sun Weide, spokesman for the Beijing Olympics organizing committee. "In terms of assembly and demonstrations, China has related laws and regulations. We hope that foreigners will respect the related Chinese laws and regulations."

Sun said the demonstrators were "persuaded to leave" by police, who received tips from local residents about the protest. The four were not arrested or taken to a police station, he said.

Tethong said the demonstrators were peacefully led away by police and members of the internal security force after about an hour. No contact had been made with them because their phones were off, she said.

"It's absolutely critical that ... a message is sent to the Chinese government to meaningfully address and end violence and repression in Tibet or they will never be truly accepted by the international community," Tethong said.

International Olympic Committee spokeswoman Emmanuelle Moreau said organizers should expect people to "use the platform of the Olympic Games to draw attention to their causes."

"The IOC are confident Beijing city authorities will assess the situation reasonably and act with tact and understanding," she said.

Tibet has been an extremely sensitive topic since protests against almost 50 years of Chinese rule turned violent in the region's capital of Lhasa in March. Many Tibetans insist they were an independent nation before communist troops invaded in 1950, while Beijing says the Himalayan region has been part of its territory for centuries.

Similar demonstrations were sparked in Tibetan communities throughout Western China and a massive crackdown by Chinese security forces ensued. Pro-Tibet groups say scores of monks and nuns have been arrested, imprisoned and beaten since March.

It could not be immediately confirmed if members of the group had breached the stadium's security perimeter. Canadian Television said the protest was outside a fence separating the public from the Olympics area.

While Beijing has announced that it would allow applications for public protests in three designated areas, it isn't immediately clear if any had been accepted.

China's human rights record and its policies in Tibet and Sudan have been a flash point in the run-up to the Aug. 8 Olympics as activists use the games to highlight their causes.

Former Olympic speedskater Joey Cheek had his visa revoked by Chinese authorities today, hours before he was set to travel to Beijing to urge the Chinese government to help make peace in the war-torn Darfur section of Sudan.

Cheek, the president and co-founder of a collection of Olympic athletes known as Team Darfur, had been planning to spend about two weeks in China.

One of his key initiatives was urging the international community to persuade Sudan to observe the ancient tradition of the Olympic truce during the Beijing Games.

More than 200,000 people have been killed and 2.5 million displaced in fighting in the western Sudanese region since ethnic African tribesmen took up arms in 2003.