ANCIENT OLYMPIA, Greece — Two men carrying the flag of a free-press group ran onto the field of the stadium in Ancient Olympia during Monday's flame-lighting ceremony for the Beijing Olympics, evading massive security aimed at preventing such disruptions in the wake of China's crackdown in Tibet.

The incident occurred while Liu Qi, president of the Beijing Olympics organizing committee and Beijing Communist Party Secretary, was giving a speech. The men were detained by some of the more than 1,000 police officers deployed around the site.

International Olympic Committee President Jacques Rogge attended the ceremony at the birthplace of the ancient games in southern Greece. The flame for the Aug. 8-24 games was lit using the sun's rays.

Greek officials said politics have no place at the event ahead of expected protests by pro-Tibetan groups. Meanwhile, China pledged strict security measures to ensure that the torch relay, which begins with the lighting ceremony, is not marred by protests.

The black flag carried by the protesters in the stadium shows handcuffs used to symbolize the five Olympic rings. The banner belongs to the Paris-based journalism advocacy group Reporters Without Borders.

China's Communist leadership has faced a public relations disaster since demonstrations against Chinese rule turned violent March 14 in the Tibetan capital of Lhasa, sparking waves of unrest in surrounding provinces. People who sympathize with the Tibetan cause have also staged rallies in other countries.