BEIJING, Aug. 6 (Xinhua) -- Four foreigners, three men and one woman, were detained here on Wednesday for displaying "Free Tibet" banners, said Beijing police department officials.

    The four gathered at around 5:47 a.m. at the Beichen Overpass near the National Stadium, or Bird's Nest, in Chaoyang District. Two men climbed up two electricity poles and hung the banners, said a police official.

    One banner was written with large black letters declaring "One World One Dream Free Tibet," and another with "Tibet will be free" in English and "Free Tibet" in Chinese.

    The police rushed to the scene 12 minutes later and persuaded them to leave, said the official.

    A preliminary investigation showed the two British and two U.S. citizens had entered China on tourist visas.

    Sun Weide, a Beijing Organizing Committee of the 29th Olympic Games (BOCOG) media official, later expressed strong disapproval of the foreigners' behavior.

    "We resolutely oppose such behavior." The Olympic Games were a grand international sports gathering and "we are resolutely against any attempts to politicize the Games."

    "China has stipulated laws and regulations concerning gatherings and demonstrations. We hope foreigners who come to China can observe China's laws and regulations."

    The case was under investigation, Sun said.

    Also Wednesday, three American anti-abortionists staged a sit-in and shouted slogans outside the National Museum of China to the east of the Tian'anmen Square in downtown Beijing in the afternoon.

    The three, including two men and a woman, were persuaded by police to leave about 30 minutes later.