Foxconn, the Taiwanese electronics firm that assembles Apple’s iPhones, said Monday that its factories in Shenzhen, China, would suspend operations after the city imposed a seven-day coronavirus lockdown.

Shenzhen borders Hong Kong, which has reported nearly 3,780 Covid-19 deaths and nearly 700,000 new cases since late January. While infections in the rest of China remain low compared with the rest of the world, the number of reported cases is growing rapidly. China’s National Health Commission reported 3,122 new cases on Sunday, about double the amount on Saturday and three times that on Friday.

Shenzhen, an electronics manufacturing hub with a population of 17 million, reported 66 new cases on Sunday. It will be shutting down most businesses and public transportation in the city and is requiring nonessential workers to stay home.

In a statement, Foxconn said that it had “adjusted the production line” to other plants in China to minimize any impact and would be requiring all employees to take P.C.R. tests.

The Shenzhen government will determine when the plant, as big as a midsize city, can reopen, the company said.

Shenzhen’s lockdown might disrupt global supply chains. An outbreak in the city last year held up port operations, causing a surge in global shipping rates and the prices of many goods.