BEIJING - Police detained journalists at a rare protest Monday in Beijing, staged by a free-press advocacy group that accuses the government of failing to meet promises for greater media freedom a year before the 2008 Olympic Games.

The detentions, which came during a visit to Beijing by International Olympic Committee president Jacques Rogge, followed the unfurling of posters depicting the Olympic rings made from handcuffs by members of Reporters Without Borders on a pedestrian bridge outside the headquarters of the Beijing Olympics planning committee.

The Paris-based group said China continues to restrict press freedoms and lock up journalists, political dissidents and activists who publish on the Internet -- despite pledges to liberalize made when bidding to stage the Games.

"Most important is that we didn't come to call for a boycott,'' said Vincent Brossel of the group. "We are calling for concrete achievements, the release of political prisoners, opening of web access and an end to radio jamming.''

The Beijing Olympics, which begin Aug. 8, 2008, are a huge source of pride for China. In bidding for the Games back in 2001, Chinese leaders promised International Olympic Committee members that the Olympics would lead to an improved climate for human rights and media freedoms.

Foreign journalists were promised "complete freedom to report.''

Yet, police in and out of uniform physically restrained reporters coming down from the pedestrian bridge, pushing and pulling them, seizing IDs and refusing to allow them to leave the scene. Reporters were detained in a parking lot directly opposite the Olympics office tower, facing the Beijing 2008 logo and Olympic rings emblazoned on the building's surface.

Journalists were allowed to leave after about two hours, with no explanation from police about why they were detained.

A long list of domestic and international groups are keen to use the Olympic spotlight to publicize their grievances with Beijing, ranging from human rights organizations, to the banned Falun Gong spiritual sect and activists trying to pressure China to use its influence with Sudan to end the suffering in Darfur.

Chinese police and government research organs are reportedly compiling dossiers of scores of groups and individuals that could cause disruptions at the Games.

China has also shown no sign of relaxing its strict controls on domestic media and the Internet, blocking many foreign websites deemed to carry politically sensitive content and imprisoning people who mail, post online, or access such information within China.