People have been beaten and detained after protests by staff working at a huge factory making iPhones in the central Chinese city of Zhengzhou.
Footage posted online shows hundreds of workers involved in demonstrations with some smashing surveillance cameras and windows.
Video shows police in masks, along with other officials in white hazmat suits, swinging batons and sticks at protesters.
On social media, staff have been complaining about pay, claiming new staff were persuaded to work at the huge factory – where 70% of iPhones are made – in return for bonuses.
A protest erupted on Tuesday after claims the operator, Foxconn, changed those terms.
Last month, thousands of employees at the site walked out over complaints about unsafe working conditions because of coronavirus cases in the facility.
Meanwhile there’s wider frustration with the ultra-strict COVID-19 restrictions in China, where millions have been confined to their homes with little warning, for weeks at a time.
Protests have flared as the number and severity of outbreaks have risen across China, including in Beijing. Recently authorities reported the country’s first COVID-19 deaths in six months.
In October, following rising COVID-19 cases in Zhengzhou, Foxconn put the plant’s 200,000 workers under closed-loop management – a system where staff live and work on site, isolated from outside.
That prompted some migrant workers to flee the plant’s campus and return to their hometowns.
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Earlier this month, the Chinese government called on retired military and government workers to help boost production at the factory because of COVID staff shortages, even offering bonuses.
And previously Apple warned people would have to wait longer for the latest iPhone 14 models because Chinese officials were imposing tougher COVID-19 restrictions.
It said the plant was “operating at significantly reduced capacity”, and Foxconn predicted smartphone revenue would fall in the fourth quarter.
The Reuters news agency forecast output at the site could drop by as much as 30% in November.