Thousands of workers have gone on strike at a Foxconn plant in China making components for Apple's iPhone 5, a labour rights group said on Saturday. It is the latest unrest to hit the Taiwanese electronics manufacturing giant, whose factories in China have been beset by a string of worker suicides in recent years, and follows a massive brawl at one facility last month. The stoppage at the plant in Zhengzhou, in central China, happened on Friday after the company increased product quality levels and demanded workers work through a national holiday, New York-based China Labour Watch said. "This strike is a result of the fact that these workers just have too much pressure," China Labour Watch director Li Qiang said in a statement. "According to workers, multiple iPhone 5 production lines from various factory buildings were in a state of paralysis for the entire day," the statement said. Between 3,000 and 4,000 employees participated in the strike, it said. It was not immediately clear how many people work at the plant. Officials at the factory were not immediately available for comment, nor were spokesmen for Foxconn's Taiwanese parent company Hon Hai or Apple's China-based public relations officials. Foxconn is the world's largest maker of computer components and assembles products for Apple, Sony, Intel and Nokia, among others. Its vast plants in China employ up to 1.1 million workers, with nearly half of them at a sprawling complex in Shenzhen, in the south of the country. Last month, around 5,000 police were deployed to control a huge brawl among workers at a Foxconn plant in the northern city of Taiyuan, where 79,000 people make items including electronic components for automobiles and consumer products. In 2010, at least 13 Foxconn employees in China died in apparent suicides, which activists blamed on tough working conditions, prompting calls for better treatment of staff.