BEIJING -- The Chinese mainland on Sunday reported 21 newly confirmed COVID-19 cases, including six locally transmitted cases and 15 arriving from outside the mainland, the National Health Commission said Dec 28.

All of the locally transmitted cases were reported in northeast China's Liaoning province, the commission said in its daily report. No new deaths related to the disease were reported.

A new suspected case arriving from outside the mainland was reported in Shanghai on Sunday, said the commission.

Sixteen COVID-19 patients on the mainland were discharged from hospitals following recovery on Sunday.

By the end of Sunday, a total of 4,218 imported cases had been reported on the mainland. Among them, 3,948 had been discharged from hospitals following recovery, and 270 remained hospitalized. No deaths had been reported among the imported cases.

The total number of confirmed COVID-19 cases on the mainland reached 86,976 by Sunday, including 339 patients still receiving treatment.

A total of 82,003 patients had been discharged from hospitals following recovery on the mainland, and 4,634 had died as a result of the virus, according to the commission.

There was one suspected COVID-19 case on the mainland as of Sunday, and 11,791 close contacts remained under medical observation.

Sunday saw 20 asymptomatic cases newly reported, 16 of whom arrived from outside the mainland. Four asymptomatic cases were re-categorized as confirmed cases on the same day.

A total of 267 asymptomatic cases were under medical observation, of whom 219 arrived from outside the mainland.

By the end of Sunday, 8,610 confirmed COVID-19 cases, including 137 deaths, had been reported in the Hong Kong Special Administrative Region (SAR), 46 cases in the Macao SAR, and 785 cases, including seven deaths, in Taiwan.

A total of 7,474 COVID-19 patients in the Hong Kong SAR had been discharged from hospitals following recovery, 46 in the Macao SAR, and 653 in Taiwan.