Beijing  - Beijing police have ordered six pro-Tibet activists - all Americans - to 10 days in detention in the harshest treatment so far of Tibet activists since a series of demonstrations in the capital during the Olympics.

The police faxed a statement Friday saying the six were arrested on Tuesday for "disturbing public order". Chinese law allows police to force people to undergo administrative detention without trial.

Police gave few details other than that one of the six was named Thomas.

The detained were believed to be the same six from the US-based group Students for a Free Tibet, which had held eight pro-Tibet protests in Beijing since August 6.

Kate Woznow, the group's campaign director, told Deutsche Presse- Agentur dpa that they had not actually protested, but had documented, including filmed, some of the protests.

"They're not guilty of any crime. They were just citizen journalists," said Woznow by phone. The six were detained after five protestors from the group were held Tuesday for unfurling a Tibet banner.

One of the six, Brian Conley, 28, sent the group a text message Tuesday afternoon saying they had been detained since 3 am, Woznow said. He also sent a message to his wife saying he was in jail, but was OK.

The six activists are all men and had entered China on tourists visas. They were living separately.

One of them, James Powderly, 31, is an artist who went to Beijing to participate in an art exhibition in late July but dropped out of the event when he was forbidden from displaying artwork with a political theme.

He was planning to project a pro-Tibet image on a building in Beijing.

The others detained are: Jeffrey Rae, 28; Tom Grant, 39, a filmmaker; Michael Liss, 35, and Jeff Goldin, 40.

Other than the six men, Beijing police detained and deported 45 protestors, Woznow said. Police usually put them on flights the same day or next day.

The deported protestors came from seven countries, including the United States, Britain, Canada, Germany and Japan. They included a Tibetan-Japanese and two Tibetan-Germans.

It was unclear why Beijing decided to hold the latest six detainees longer, but China can be more annoyed with negative publicity than the protests themselves.

All of the activists, some of whom have traveled to Tibet, were hoping that by speaking out and demonstrating in China, they could push for an improvement of the situation in Tibet, which is under a clampdown by Chinese authorities following a March uprising.

"These people of conscience from many walks of life were here to make sure the Tibetan issue was at the forefront during these Olympics Games," said Woznow.

A spokeswoman for the US Embassy in Beijing told dpa that the embassy was aware that Beijing police have detained six Americans affiliated with five protestors arrested for unfurling a banner, but she could not provide details owing to privacy concerns.

"We encourage the government of China to demonstrate respect for human rights, including freedom of expression and freedom of religion of all people during the Olympic Games and beyond," said spokeswoman Susan Stevenson.

"These rights are protected by China's own constitution and international human rights standards to which China has agreed." (dpa)