Chinese mainland reported 103 confirmed COVID-19 cases in the 24 hours ending midnight Sunday, said the National Health Commission, making it the steepest increase in a single day in more than five months.

The last time the commission reported a three-digit rise in 24 hours was in July 2019, with 127 confirmed cases.

Of the newly-added cases on Sunday, 85 infections are locally transmitted, among which 82 were in Hebei province, the commission added. 

Two other cases are in Northeast China's Liaoning province, and one in Beijing, the commission said in a statement on its website on Monday.

No coronavirus induced-deaths or suspicious cases were reported, but the number of critically-ill cases increased by four over the period, the statement added. 

Shijiazhuang, capital of Hebei province, and the nearby city of Xingtai, began reporting locally transmitted infections on Jan 2.

The commission also reported 18 imported infections over the period, mostly in Guangdong and Liaoning provinces, Tianjin and Shanghai. That has driven the imported caseload to 4,430, with 298 still hospitalized. 

The past 24 hours saw 18 patients discharged from hospitals and 405 close contacts of infected people released from quarantine, it said.