China's much-touted dynamic zero COVID policy came under sharp criticism from the WHO which termed it unsustainable in view of the constantly changing behaviour of the coronavirus and called on Beijing to shift its strategy.

World Health Organisation (WHO) Director-General Tedros Adhanom Ghebreyesus said this on Tuesday while commenting on China's zero COVID policy under which many Chinese cities, including Shanghai and Beijing, were either under lockdown or semi-lockdown for prolonged periods.

As we all know the virus is evolving, changing its behaviour and becoming more transmissible. With that changing behaviour, changing your measures will be very important, Tedros said.

When we talk about zero COVID strategy, we don't think it is sustainable considering the behaviour of the virus now what we anticipate in the future, especially when we have now the good knowledge and understanding of the virus, he told a media briefing in Geneva.

With the availability of good tools, transiting into another strategy will be very important, Tedros said in the recording of his press conference circulated by the WHO to the media.

"We have discussed about this issue with Chinese experts and we indicated that the approach will not be sustainable, considering the behaviour of the virus I think a shift will be very important," he said in strong comments critical of China's zero COVID policy pursued vigorously by Beijing under the directives of Chinese President Xi Jinping.

On Wednesday, China's National Health Commission reported 1,847 cases, mostly from Shanghai, the country's business hub with over 25 million population, which remained under lockdown for over a month.

Also, the capital Beijing, which is under semi-lockdown, conducted the ninth nucleic acid test on Wednesday for its over 21 million people. The 10th test will be conducted on Thursday.

As China continues to wage a grim battle to curb the spread of the Omicron variant, President Xi has been prodding officials to strictly adhere to the much-criticised dynamic zero-COVID policy, saying that the epidemic prevention has reached a crucial stage.

In his much-publicised comments at the ruling Communist Party's high power political bureau meeting in Beijing to review the COVID-19 situation on May 4, President Xi stressed that epidemic prevention and control is at a critical stage and called for efforts to adhere to the dynamic zero-COVID policy.

Last week, China cancelled the 2022 Asian Games scheduled to be held in Hangzhou in September and the World University Games due to start in Chengdu in late June.

Defending the zero COVID policy under which China has also cancelled flights with several countries, including India, for over two years, Chinese Foreign Ministry spokesman Zhao Lijian late last month told reporters that China is currently facing an Omicron tsunami.

This variant spreads very fast, much faster than we can imagine, he said.

Zhao said that China brought under control the Delta variant attack in 2021 in about 14 days but the Omicron attack was far more severe.

Since the deadly coronavirus first emerged in the central Chinese city of Wuhan in late 2019, it has claimed the lives of 62,55,791 people and infected more than 51,87,94,928.