GUANGZHOU -- The city of Dongguan in South China's Guangdong province on Saturday added a medium-risk area for COVID-19 outbreak, according to the city's epidemic prevention and control headquarters.

The move comes after a new confirmed COVID-19 case was reported on Friday in a residential quarter in the city's Nancheng sub-district. The new case is the wife of a COVID-19 patient earlier confirmed in Shenzhen.

As of 5 pm Friday, 163 close contacts of the new case had been put under medical observation.

The city has initiated mass nucleic acid testing covering residents in areas where the case had visited. Restrictions on personnel movement have also been enforced in certain areas.