The five unfurled banners at a base camp of the world's highest mountain on the eve of an announcement of the Olympic torch route for next summer's Olympic Games calling for an independent Tibet.
The Foreign Ministry said that the five were detained for "carrying out illegal activities aimed at splitting China," and that they had been expelled according to Chinese law.
Organizers for the Beijing 2008 Summer Olympics announced the route on Thursday, revealing ambitious plans for the longest torch relay in Olympic history — a 85,000-mile, 130-day route that would cross five continents and scale Mount Everest.
China says it has ruled Tibet for centuries, although many Tibetans say their homeland was essentially an independent state for most of that time. Chinese communist troops occupied Tibet in 1951 and Beijing continues to rule the region with a heavy hand.
Taking the Olympic torch to the top of the 29,035-foot Mount Everest is seen by some as a way for Beijing to underscore its claims to Tibet, and is expected to be one of the relay's highlights.
The four Americans and one Tibetan-American who were detained on Everest, which straddles Nepal and Tibet, had waved a banner reading: "One World, One Dream, Free Tibet 2008." The slogan of the Beijing Games is "One World, One Dream."
An official for their group, Students for a Free Tibet, had initially said four people were detained, but later said a fifth, who was transporting videotape, had also been held.
"We are very happy to know they have been freed," said Lhadon Tethong, the group's executive director. She identified the five as Kirsten Westby of Boulder, Colorado; Tenzin Dorjee of New York; Jeff Friesen of Vancouver, Washington; and Shannon Service and Laurel Mac Sutherlin of San Francisco.
Tethong also criticized the International Olympic Committee for allowing the Beijing organizers to route the torch relay through Tibet.
"This is no thanks to the IOC," Tethong said by telephone from Nepal's capital, Katmandu. What will the future of Tibet be like if the Chinese are allowed to carry out their propaganda?"
Although the IOC has regulations on the torch route, it is the local organizers who decide where the flame goes.
"Tibet is an integral part of China's territory, and the Chinese government and people will never tolerate any activities to split it," the ministry statement said.
It did not say where the five would be expelled to, but Tethong believed it would be Nepal.
Politics have also overshadowed China's bid to have the torch go through Taiwan, with the head of Taiwan's Olympic Committee saying the planned route was not acceptable.