Pro-democracy lawmaker Leung Kwok-hung, also known as "Long Hair", sticks a protest sign in support of a strike by workers of Yue Yuen Industrial Holdings in Dongguan, during International Labour Day in Hong Kong May 1, 2014. Chinese police have placed labour activist Lin Dong under criminal detention, formally accusing him of causing a disturbance after they said he distributed information online about a factory strike, his manager and father said on Tuesday. In what activists say was one of China's biggest labour protests since market reforms began in the late 1970s, Yue Yuen workers went on strike in the southern city of Dongguan on April 14, to protest against what they said were chronically low company contributions to social insurance and housing provident fund accounts. Yue Yuen said on Friday that more than 80 percent of its 40,000-strong workforce had returned to work. Yue Yuen Industrial Holdings is a $5.6 billion manufacturer of footwear for Nike Inc, Adidas AG, and other international brands. The signs read, "Sweat factory", "Release the arrested activists (Lin and others)" (top 2nd R) and "Multinational profiteering" (top R). REUTERS/Tyrone Siu (CHINA - Tags: POLITICS BUSINESS EMPLOYMENT CIVIL UNREST)