China has been seeing a rapid surge in the number of new coronavirus cases across the country since the government eased its zero-COVID containment policy on December 7.

The Japanese embassy in Beijing says many employees of Japanese firms in China are testing positive, and are being instructed to work from home. More plants are also operating at smaller capacities.

Health authorities in Qingdao, Shandong Province, last Friday estimated that the numbers of new infection cases have been increasing by between 490,000 and 530,000 people per day.

The city in eastern China is home to many Japanese firms.

The head of Japan External Trade Organization's office in Qingdao, Yoshikawa Akinobu, told NHK that the virus began quickly spreading around December 16.

Yoshikawa says there are Japanese firms that see 30 to 40 percent of their workforce testing positive.

Production at some firms has dropped by nearly half, although they are trying to maintain operations with the workers they have.

The Japanese embassy says some Japanese firms have reported that their employees are returning to offices as coronavirus infections have likely peaked in Beijing.

The Chinese Center for Disease Control and Prevention announced that new COVID-19 cases nationwide reached 2,637 on Sunday.

The center says confirmed cases in Zhejiang Province were just 19, an extremely small number compared to a figure of one million new cases a day reported by health authorities in the province the day before.

The tally in Shandong Province was 21. The center's figure also shows large discrepancies with daily numbers released by health authorities in Qingdao in the province last Friday.

The number of deaths announced by the center has totaled less than ten this month, with no deaths being reported between December 20 and 25.