China's Hong Kong Special Administrative Region (HKSAR) on Thursday announced stricter quarantine measures for visitors from outside China.

Starting Friday, visitors who have been to places outside China over the past 21 days will be put in quarantine for 21 days, instead of the current 14 days, in designated hotels, the HKSAR government said in a statement. 

Three days earlier, Macao SAR announced to take the same measures, but people from the HKSAR are among those to be quarantined for 21 days.

The SAR governments of both Hong Kong and Macao said the new policies have been adopted as the incubation period of the coronavirus in a small minority of patients could be longer than 14 days.

Hong Kong will also deny entry to visitors who have stayed in South Africa for more than two hours over the past 21 days to prevent the import of a new variant of coronavirus. The government imposed a similar ban on visitors from Britain earlier this week.

Hong Kong's Centre for Health Protection (CHP) reported 71 additional confirmed cases of COVID-19 on Thursday, taking its total tally to 8,424.

The new cases included 61 local infections, with 30 cases of unknown origin, according to a CHP press briefing. Three out of the 10 cases from overseas were from Britain. There were also about 50 preliminary cases.

According to Hong Kong's Hospital Authority, 66 percent of negative pressure beds in the city are now occupied. Currently, 985 COVID-19 patients are being treated in public hospitals and community treatment facility at AsiaWorld-Expo, and 61 are in critical condition. The city's death toll stands at 135.

(With input from Xinhua)