Four US activists have been arrested at Mount Everest after calling for Tibetan independence and protesting against the Beijing Olympics, their group has said.
Protesters took the banner into the Chinese camp, the group said
They were detained by Chinese police after unfurling a banner at the base camp, Students for a Free Tibet said.
China will announce the route for the 2008 Olympic torch relay on Thursday.
Chinese officials have said they want to take it to the top of Everest - the world's tallest mountain on the border between Tibet and Nepal.
Their hope of taking the torch to self-ruled Taiwan, which China still sees as its territory, is also politically sensitive.
The Tibet protest took place as Chinese climbers prepared to see if it was possible to take the torch to the top of the 8,448m (29,028ft) mountain.
The three Americans and one Tibetan-American held up a banner saying: "One World, One Dream, Free Tibet 2008."
"One World, One Dream" is the 2008 Beijing Olympics slogan.
The group's executive director, Lhadon Tethong, said the four had been able to walk into the Chinese encampment.
"They had this banner, our Tibetan friend was singing the national anthem, they lit a symbolic torch for Tibetan freedom," he told Reuters news agency.
One of the protesters, Kierstan Westby of Colorado, told the Associated Press they had been treated well by the police but did not know how long they would be held.
"We were questioned separately by police and they took our passports away," she said, adding: "We are hoping they take us to the border and let us go."
China has long laid claim to Tibet and sent in troops to occupy the region in 1950.
While Beijing says the region has considerable autonomy, many Tibetans argue that their self-government exists in name only.
China has vowed to bring economic prosperity to the impoverished region, but many fear Tibet's ancient traditions as well as its delicate eco-system are at risk.