More than 3,500 people related to a COVID-19 cluster found in a workplace in Beijing's Shunyi district have been placed into quarantine as of Tuesday, senior official said.

Beijing reported a COVID-19 cluster in a data center of Beijing Rural Commercial Bank in Shunyi on Monday.

By Tuesday afternoon, the number of infections discovered in the cluster rose to 28, including 24 employees and four family members, said Pang Xinghuo, deputy director of the Beijing Center for Disease Prevention and Control, at a news conference on Tuesday afternoon.

"This cluster has a large scale and the confirmed cases visited a wide range of locations in the city, covering seven districts: Shunyi, Haidian, Fengtai, Chaoyang, Tongzhou, Changping and Xicheng," she said.

"It's expected the number of infections in this cluster will increase in near future, but the situation is under control since strong preventive measures have been taken."

According to Zhang Yanlin, deputy head of Shunyi, the district has identified 1,897 close contacts and 1,646 sub-close contacts of the new cases.

"All the contacts in Shunyi have been transferred to centralized quarantine and the information on the ones who are not in Shunyi have been delivered to the authorities of other districts," he said.

All 103 locations with infection risks have been disinfected, Zhang added. Up to 13 residential communities have been designated as controlled zones and 37 are precautionary zones.

Shunyi will conduct three consecutive nucleic acid tests from Tuesday to Thursday.