China’s top respiratory disease expert Zhong Nanshan has urged the Hong Kong government to carry out citywide Covid-19 testing to contain its third wave of local infections.

Hong Kong registered a triple-digit rise in Covid-19 cases for the eighth day running on Wednesday, pushing its total infections over 3,000 since its first coronavirus outbreak in late January.

The city’s authorities are battling to manage the burden on local hospitals as a result of the surge and are facing the additional challenge that the origin of more than half of daily infections have been untraceable since mid-July.

“My understanding is that Hong Kong people are now being tested on a voluntary basis,” Zhong said in an interview with state broadcaster CCTV. “But I think if the situation goes on like this, everyone should be made to do the test.”

The Guangzhou-based “Sars hero” also said Hong Kong’s ban on dine-in services, which took effect this week, was a crucial step to contain the outbreak. Other stringent measures introduced in the city include mandatory mask wearing in public.

While the increase in cases was concerning, they were not yet growing at an exponential rate, he said. “Hong Kong’s problem was never on the medical aspect, but on containment.”

Zhong said the mainland’s experience showed strict lockdown policies had been very successful. “The mainland would have adopted even stronger measures. But Hong Kong has its own conditions, it has too little space, population density is too high, adopting the same strict measures would cause an impact on economic development and all other areas.

“So the way out is to increase testing and discover the asymptomatic patients,” he said. Zhong explained this was because people would be subjective in judging whether they had developed symptoms, while asymptomatic patients appeared able to pass on the virus in the five days before and after they began to show symptoms.

Zhong said mass gatherings of people should be stopped and there should be more of an information exchange between Hong Kong and the mainland about how to bring the pandemic under control. “Whenever Hong Kong needs assistance, we will provide help without hesitation. There should be more exchanges on pandemic control and prevention,” he said.

However, the introduction earlier this month of free Covid-19 tests for high-risk groups amid the city’s third wave of infections has already stirred up controversy.

Local district councillors and opposition lawmakers accused the Hong Kong government of an opaque process in its decision to buy services from Shenzhen-based BGI Group and China Certification & Inspection Group which have been conducting testing in Macau. They have also expressed safety concerns.

Hong Kong authorities have been criticised for the high cost of its Covid-19 tests due to low testing ability. Chief Executive Carrie Lam Cheng Yuet-ngor said daily tests would be increased to 8,000 from next month, when additional manpower and equipment were on board.