Wang Guiqiang, head of the infectious diseases department at Peking University First Hospital, said the number of cases in Beijing might continue to increase based on the current situation, according to a report by chinanews.com on Monday.

"Some people's infections may not be detected yet. Thus, they might keep spreading the virus," he said. "The risk still exists, so we need to strengthen testing and screening."

The National Health Commission announced on Sunday that it had sent a team of experts to Beijing to guide COVID-19 prevention and control work. The team included the head of the commission, experts with experience in Wuhan and top experts in epidemiological investigation and environmental disinfection.

Facing the sudden increase in the number of local cases, the municipal education authority announced on Sunday that students who have resumed on-campus classes can choose to study at home if they wish. Students in their final year of junior high and senior high school will finish their classes 14 days in advance of the date of their final exams and study at home.

"We want to ensure the health and safety of every student," said Li Yi, a spokesman for the Beijing Education Commission. He said provision of online study materials will continue.

Students who study at school should wear masks at all times, including during classes, the commission said on Monday.

When students have outdoor activities and take part in sports, they can take off their masks while maintaining social distance, it said.