China's warning that it will not tolerate any Arab-style protests has been backed up by increased security on the streets.
Police in Beijing kept a close watch on Tiananmen Square. Security patrols were stepped up around a main shopping area, where an online call had urged people to protest.
Beijing has tightened censorship and reporting restrictions. Controls and checks on foreign tourists and journalists have also been increased.
A similar clampdown has been reported in Shanghai.