(Bloomberg) -- China’s Zhengzhou city has locked down some areas near Foxconn Technology Group’s main iPhone manufacturing base in a move that could spell further trouble for Apple Inc.’s supply chain. 

Local authorities announced late Friday they are placing some areas in the Zhengzhou Airport Economy Zone under quarantine effective immediately, according to a statement on its official WeChat account. People in the area will not be permitted to leave, according to the statement.  

The Zhengzhou Airport Economy Zone is home to the world’s largest iPhone assembly plant, where staff have been ordered to undergo mandatory Covid-testing in recent days. Foxconn and Apple didn’t immediately reply to emailed queries about whether the lockdown will affect operations.  

Read more: IPhone City Staff in China to Undergo Mandatory Virus Tests

The fresh controls mark a widening of curbs in China, which is battling its worst Covid-19 outbreak in the past two years. Major cities from Shanghai to Guangzhou have already imposed restrictions on their citizens, fueling burgeoning anger against the government. 

Fellow Apple suppliers Pegatron Corp. and Quanta Computer Inc. have halted production in eastern China to comply with local Covid-related restrictions. 

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