Video grab of Taiwanese tech giant Foxconn s iPhone factory protest, Zhengzhou, China. Photo courtesy of Bloomberg
In videos shared on Weibo and Twitter that AFP has verified, hundreds of workers can be seen marching on a road in daylight. Some were confronted by riot police and people in hazmat suits.
Foxconn confirmed the unrest later on Wednesday.
A night-time video showed a man with a bloodied face as someone off-camera says: "They're hitting people, hitting people. Do they have a conscience?"
Another at the same scene showed dozens of workers confronting a row of police officers shouting, "Defend our rights! Defend our rights!", while another voice talks of "smoke bombs" and "tear gas".
AFP verified those videos partly through geolocation that showed distinctive features, including a building and barricades near staff living quarters on the factory compound.
In a daytime video, several fire trucks surrounded by police in hazmat suits were parked near residential blocks while a voice on a loudspeaker was heard saying: "All workers please return to their accommodation, do not associate with a small minority of illegal elements."
China's unrelenting zero-Covid policy has caused fatigue and resentment among wide swaths of the population, some of whom have been locked down for weeks at factories and universities or been unable to travel freely.
The Weibo hashtag "Foxconn riots" appeared to be censored by Wednesday noon but some text posts referring to large protests at the factory remained live.
Foxconn said workers had complained about pay and conditions at the plant but denied it had housed new recruits with Covid-positive staff at the Zhengzhou factory, the world's largest producer of iPhones.
"Regarding any violence, the company will continue to communicate with employees and the government to prevent similar incidents from happening again," the Taiwanese tech giant said in a statement.
Apple did not respond to requests for comment.
Hotbed of unrest
Foxconn, also known by its official name Hon Hai Precision Industry, is the world's biggest contract electronics manufacturer, assembling gadgets for many international brands.
The Taiwanese tech giant, Apple's principal subcontractor, recently saw a surge in Covid-19 cases at its Zhengzhou site, leading the company to shut the vast complex in a bid to keep the virus in check.
The huge facility of about 200,000 workers -- dubbed "iPhone City" -- has since been operating in a "closed loop" bubble.
Footage emerged this month of panicking workers fleeing the site on foot in the wake of allegations of poor conditions at the facility.
Multiple employees later recounted to AFP scenes of chaos and disorganisation at the complex of workshops and dormitories.
In the place of the fleeing workers, the firm has offered large bonuses and other incentives for employees who stayed as the local government bussed in fresh labourers in a bid to keep the factory afloat.
Apple this month acknowledged the lockdown had "temporarily impacted" production ahead of the holiday season at the Zhengzhou factory, the Taiwanese company's crown jewel that churns out iPhones in quantities not seen anywhere else.
Foxconn is China's biggest private sector employer, with more than a million people working across the country in about 30 factories and research institutes.
China is the last major economy wedded to a strategy of extinguishing Covid outbreaks as they emerge, imposing lockdowns, mass testing and lengthy quarantines despite the widespread disruption to businesses and international supply chains.
The policy has sparked sporadic protests throughout China, with residents taking to the streets in several major Chinese cities to vent their anger against snap lockdowns and business closures.