Protests have erupted at the world's biggest iPhone factory in the Chinese city of Zhengzhou, according to footage circulated widely online. Videos show hundreds of workers marching, with some confronted by people in hazmat suits and riot police. Those livestreaming the protests said workers were beaten by police. Videos also showed clashes. Manufacturer Foxconn said it would work with staff and local government to prevent further violence. In its statement, the firm said some workers had doubts about pay but that the firm would fulfil pay based on contracts. Last month, rising Covid cases saw the factory locked down, prompting some workers to break out and go home. The company then recruited new workers with the promise of generous bonuses. But one worker said these contracts were changed so they "could not get the subsidy promised", adding that they were quarantined without food. The Zhengzhou plant employs more than 200,000 people, making Apple devices including the iPhone 14 Pro and Pro Max.