As China tightened security around Tiananmen Square Saturday to prevent memorials on the anniversary of the bloody 1989 crackdown on pro-democracy protestors, tens of thousands in Hong Kong staged a candlelight rally to mark the anniversary. In Sydney, Chen Yonglin, a 37-year-old Chinese diplomat who is seeking political asylum in Australia, said at a memorial rally that he was seeking asylum because of a lack of political freedom and human rights in China.