many uighurs chafe at chinese controls on their religion, culture and language, although the government denies imposing restrictions on these activities. uighur dissatisfaction has sometimes erupted into violence. in 2009, nearly 200 people were killed in rioting. the group's leader called for an international investigation into the incident near tiananmen square. >> translator: the chinese government hasn't told the media what really happened at the scene. the coverage is based on the story the government made up. and it lacks credibility. >> reporter: u.s. officials expressed concern over the chinese government's abuse of the group's human rights. >> we believe, of course in human rights across the board. that certainly applies to the uighur community. and that's something that we communicate regularly. >> reporter: chinese law calls for severe punishment for acts of terror. officials say such penalties ensure the protection of human rights and social order. authorities have cited the fight against terror as a motive for tightening security both in the capital and throughout the count