Following a weeks-long lull in new coronavirus COVID-19 cases, Beijing has recorded dozens of new cases in recent days.
According to Reuters, all the new cases have been linked to a major wholesale food market in the city.
On Sunday night Beijing ordered all companies to supervise 14-day home quarantine for employees who have visited the Xinfadi market.
The same applies to any employees who have been in contact with anyone who visited the market.
At least 10 Chinese cities, including Harbin and Dalian, have urged residents not to travel to the capital.
As in other countries, China hopes to stop a second wave from emerging after easing lockdowns that hammered its economy earlier this year.