Dozens of leftists scuffled with hundreds of supporters of writer and critic Li Chengpeng during a book signing in Shenzhen yesterday. More than 2,000 Li fans, ranging from university students to office workers and retirees, waited outside Shenzhen Book City before the event started at 6pm. Li, a former journalist based in Chengdu , Sichuan , was punched in the head by a leftist during a book signing in Beijing on Sunday. That attack sparked an outcry, especially on social networking sites. "I would hardly be here to buy Li's book if not for what happened to him on Sunday," one young man said. "I just came here to show my support for Li, a liberal-minded critic." He bought a signed copy of Li's new book, The Whole World Knows . Meanwhile, dozens of protesters, most in their 40s or 50s and some wearing Mao Zedong badges, gathered outside the building. One of the protesters said he was outraged by some of Li's recent comments, such as labelling those who took to the streets in anti-Japanese demonstrations in Shenzhen "brain damaged". "Li is a typical traitor who does nothing more than distort history and mislead the public, particularly the young," he said. Although dozens of policemen, most in plain clothes, were at the scene, the two groups of people clashed at least three times between 6pm and 7pm, with some suffering minor injuries. At one stage a middle-aged, bespectacled man shouted "Li Chengpeng a traitor!" The man slapped one of Li's supporters in the face when he tried to stop him from hurling abuse at Li, who was protected by six bodyguards. Li did not stop signing copies of his book until 9.30pm and then began signing copies of earlier books brought along by dozens of his fans.