Foxconn was forced to close doors at a plant in Taiyuan, south of Beijing, after a riot involving more than 1000 staff, The New York Times reports.
Chinese state-run media reports, relayed by the Times, say 5000 police were brought in to control an all-in brawl, in which 40 were injured.
Foxconn would not comment on whether the iPhone 5 is assembled at Taiyuan plant.
However, the Times quotes an employee who says the plant, which employs 79,000, is used for the iPhone.
Foxconn employs 1.1 million in a series of giant factories. It assembles consumer electronics on contract to a number of Western manufacturers, including Apple.
The fight began after an argument between workers and security guards. The cause of the argument is now known. (But could it explain the alleged scuffs and scratches? – Editor.
Foxconn has been repeatedly targeted by some in the West who have alleged poor conditions, but one US broadcaster was forced to recant a report that was exposed as a fabrication.
Decline and fall of Western Civilisation – or not
On the eve of the iPhone 4's release, President Obama asked Steve Jobs why the handset could not be made in the US.
But NBR ONLINE considers that Apple, now the world's most valuable company, has done well to farm out assembly and focus on design, marketing and other tasks higher up the food chain.
In any case, Foxconn will need to reopen the plant's doors quick sharp, for the iPhone 5 has sold out on record orders.