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.
It also described as “patently untrue” rumours.