(Bloomberg) -- China’s Zhengzhou — the capital of Henan province known as “iPhone City” — relocated 870 workers to a hub about 230 miles away in a neighboring province, without giving them any advance notice about the measure to curb Covid transmission.

Most Read from Bloomberg

• Scientists Revive 48,500-Year-Old ‘Zombie Virus’ Buried in Ice

• These Are the Best and Worst Cities for Expats to Live and Work In

• Banks Stuck With $42 Billion Debt Seize Chance to Offload It

• NYC Becomes One Billionaire Family’s Haven From China Property Crash

The workers were transported to Xuzhou in Jiangsu province early Friday “without prior communications,” the city’s authorities said in a statement Saturday on its official WeChat account. It didn’t say whether any of the people tested positive.

Zhengzhou, home to Apple Inc.’s largest iPhone manufacturing site, shot to global prominence after videos emerged on social media showing hundreds of workers in violent clashes prompted by anger over unpaid wages and concern over virus infections. Apple’s main global production partner, Foxconn Technology Group, later began offering 10,000 yuan ($1,395) to any worker who chose to leave.

Most of the people have since been transferred to other locations via a so-called closed-loop arrangement, the statement from Xuzhou city said. The rest were placed in another pandemic bubble system that limits contact with the outside world. The people were all former employees of a “key enterprise” in Zhengzhou’s airport economic zone, it added, without saying which enterprise. A Foxconn representative didn’t reply to queries out of business hours Saturday.

Zhengzhou announced earlier this week a lockdown of its main urban areas for five days as local officials sought to quell a swelling outbreak. While the areas under so-called “mobility controls” didn’t include the district where Foxconn is located, the iPhone plant is in an area already classified as high risk, which means lockdown-like movement restrictions remain in place.

China Locks Down City With World’s Largest IPhone Factory

Xuzhou said local Covid risks are controllable, and now require citizens to present a negative test result within 48 hours to enter public venues, shortened from a previous 72 hours.

--With assistance from Gao Yuan.

Most Read from Bloomberg Businessweek

• Car Price Divergence Hints at More Painful Inflation Ahead

• Tesla’s Lithium Lead at Risk as Rivals Make Supply Deals

• TikTok’s Viral Challenges Keep Luring Young Kids to Their Deaths

• How to Keep Your Investments Halal

• Global Debt Costs Are Soaring. Here’s Where It Will Hurt Most

©2022 Bloomberg L.P.