The Chinese city of Zhengzhou has locked down some areas near Foxconn Technology Group’s main iPhone manufacturing base, with state media reporting operations remaining normal amid concern of further problems for Apple Inc’s supply chain.

Local authorities announced on Friday that they are quarantining some areas of the Zhengzhou Airport Economic Zone with immediate effect, according to a statement on their official WeChat account. People in the area will not be able to leave, according to the statement.

The Zhengzhou Airport Economic Zone is home to the world’s largest iPhone assembly plant, where employees have been forced to undergo mandatory Covid tests in recent days. Foxconn and Apple did not immediately respond to emailed questions about whether the lockdown will affect operations.

The China Securities Journal reported Saturday that Foxconn’s factories in the area are operating normally, citing unnamed company executives.

iPhone City employees in China will undergo mandatory virus testing

The new controls mark an expansion of restrictions in China, which is facing its worst Covid-19 outbreak in two years. Major cities from Shanghai to Guangzhou have already imposed restrictions on their citizens, fueling growing anger against the government.

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