The Chinese mainland on Sunday reported 18 newly confirmed COVID-19 cases, all of which were imported cases, the National Health Commission said Monday.

Residents line up to have their swab samples collected for nucleic acid testing of possible COVID-19 infection at a testing site in the Xinxing community in Bayuquan District, Yingkou City, northeast China's Liaoning Province, on May 21, 2021. (Xinhua/Pan Yulong)

Of the imported cases, three each were reported in Shanghai, Guangdong and Sichuan, two in Shaanxi, and one each in Tianjin, Inner Mongolia, Heilongjiang, Jiangsu, Fujian, Hunan and Gansu.

There were 294 active imported cases as of Tuesday. No deaths related to the disease were reported, while eight COVID-19 patients were discharged from hospitals.

The total number of confirmed cases on the Chinese mainland stood at 90,991, with the death toll unchanged at 4,636.