World Health Organization (WHO) Director-General Tedros Adhanom Ghebreyesus said Tuesday that China's stringent "zero-COVID" strategy is "not sustainable" because of the omicron variant. 

The remarks follow similar comments last week that drew criticism from China, calling the statements "irresponsible."

"We know the virus better and we have better tools, including vaccines, so that’s why the handling of the virus should actually be different from what we used to do at the start of the pandemic," Tedros said. 

LOCKDOWNS REMAIN IN SHANGHAI EVEN AFTER CITY HITS 'ZERO COVID' MILESTONE

He noted that the virus had changed significantly since it was first identified in late 2019.

Tedros said that while his agency had advised Chinese leaders about their pandemic response, it remains "up to every country" to make their choice of policies.

A COVID test in Beijing

Resident gets a throat swabbed during a mass COVID test set up outside a shuttered commercial office complex on Tuesday, May 17, 2022, in Beijing.  (AP Photo/Andy Wong)

While leaders of the nation's largest city, Shanghai, are aiming to loosen restrictions following harsh measures that have confined millions to their homes for weeks, China's capital city has resisted sweeping lockdowns despite recent outbreaks. 

In Shanghai, authorities said Monday that fewer than 1 million people remain under strict lockdown. 

"The epidemic in our city is under effective control. Prevention measures have achieved incremental success," Vice Mayor Zong Ming told reporters, noting that 15 out of Shanghai’s 16 districts had eliminated virus transmission among those not already in quarantine.

UNIVERSITY STUDENTS PROTEST COVID RESTRICTIONS AT TOP BEIJING INSTITUTION

Supermarkets, malls and restaurants were allowed to reopen on Monday with limits on capacity and mandated "no contact" transactions. 

However, most of the city’s 25 million people remain under some form of restriction and the subway train system remains closed for now.

In Beijing, more daily testing has been ordered, classes have been suspended and subways have been shuttered.

Chinese authorities extended work-from-home rules in four of Beijing's 16 districts on Sunday.

Some residential communities are under lockdown and people have been warned to avoid traveling between city districts.

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Restaurants are restricted to takeout service, and many shops and tourist sites are closed.

Fox News' Anders Hagstrom and The Associated Press contributed to this report.