BEIJING - Cities in central China hastily drew up plans to isolate migrant workers fleeing to their hometowns from a vast assembly facility of iPhone maker Foxconn in COVID-hit Zhengzhou city, fearing the returnees may trigger coronavirus outbreaks.

Zhengzhou, capital of Henan province, reported 167 locally transmitted COVID-19 cases in the seven days to Oct. 29, up from 97 infections in the prior seven-day period. Taiwan-based Foxconn, which has about 300,000 workers in Zhengzhou, has not disclosed the number of infected workers.

Under China's ultra-strict zero-COVID policies, localities are mandated to act swiftly to quell any outbreaks, with measures that could include full-scale lockdowns. On Oct. 19, Foxconn banned all dining-in at canteens and required workers to take their meals in their dormitories, but assured that production was normal.

Photographs and videos circulating widely on Chinese social media since Saturday showed Foxconn workers trekking across fields in the day and along roads at night. Reuters could not immediately verify the authenticity of the posts.

In an apparent show of support, residents in the vicinity left bottled water and provisions next to major roads with signs such as: "For Foxconn workers returning home", according to social media posts.

A Foxconn official had no immediate comment in response to Reuters queries.

"They were Foxconn employees who escaped from the factory and were walking home," wrote a user of WeChat in a post about the social media images.

"Some people were walking amid wheat fields with their luggage, blankets and quilts. I couldn't help but feel sad."

Late on Saturday, cities near Zhengzhou including Yuzhou, Changge and Qinyang, as well as the Weiqu district and Xihua county in the city of Xuzhou, urged Foxconn workers to report to local authorities in advance about plans to return home.

Returning workers are to travel "point-to-point" in pre-arranged vehicles en route, and are to be quarantined on arrival, they said in separate letters on their respective social media accounts addressed to Zhengzhou Foxconn workers.

Xihua county said it was organising a special vehicle from Sunday to bring back directly from the Foxconn plant workers who were originally from the county, assuring them that they would not be turned away but that counter-epidemic measures needed to be observed.

(Reporting by Ryan Woo and Ziyi Tang; Editing by Edmund Klamann)