The Chinese government has ordered some of its biggest companies, including iPhone maker Foxconn and oil producer CNOOC Ltd., to operate within a "closed loop" restricted system for seven days due to the latest COVID-19 outbreak in Shenzhen, Bloomberg News reported Monday.

The Shenzhen government has asked its 100 biggest companies, including BYD Co, Huawei Technologies Co, and ZTE Corp, to restrict operations only to employees living within a closed loop, with little to no contact with people beyond their plants or offices, the report said, citing a Shenzhen government notice.