Guangzhou, Guangdong province, reported four new locally transmitted COVID-19 cases on Wednesday, indicating the coronavirus outbreak has not ended in the southern metropolis, a senior health official said.

All the patients who were identified on Wednesday are residents of the Heyuan community in Guangzhou's Liwan district who had previously been isolated in hotels for medical observation, said Chen Bin, deputy director of Guangzhou municipal health commission.

All close contacts of the four patients have now been quarantined, she said at a news conference on Thursday.

No local asymptomatic carriers were reported on Wednesday, nor did the city have any locally transmitted COVID-19 cases on Tuesday.

Chen urged residents to be patient and never relax their vigilance or adopt blind optimism about progress against the coronavirus.

"Residents should continue to strictly abide by relevant measures introduced by the provincial and city governments when a risk of being infected still exists," she said.

To help curtail the coronavirus, Chen said mass testing and vaccinations will continue in the weeks ahead. She urged people to wear face masks, maintain social distance, pay attention to personal hygiene, avoid parties and banquets and refrain from visiting the crowded places.

As of 6 pm on Wednesday, test samples had been collected for 536,086 residents living in the southern part of Liwan district. All results came back negative, Chen said.

Guangzhou had reported a total of 151 locally transmitted COVID-19 cases, including 144 confirmed cases and seven asymptomatic carriers in this round of the outbreak, which started in May.

In addition to the four patients infected locally in Guangzhou, Guangdong province reported another three imported confirmed cases on Wednesday that were traced to Shenzhen, plus 11 imported asymptomatic carriers.

As of Wednesday, Guangdong had reported a total of 2,657 confirmed COVID-19 cases, including 1,101 imported ones, with 218 patients still hospitalized.