SHANGHAI - China's northeastern city of Harbin will conduct a city-wide exercise to test its roughly 10 million people for COVID-19 from Monday, although it has had no recent cases, calling it an pre-emptive move ahead of the long Lunar New Year holiday.

The city government said on its official WeChat account it had made the decision in view of how the week-long holiday, which officially starts on Jan. 31, was a peak travel period for the country.

"Many cities recently reported cases of the local Omicron infection so prevention and control has to be very rigorous," the Harbin government added.

Cities across China have in recent weeks imposed tougher restrictions to try to control new outbreaks of COVID-19, a task that has also taken on extra urgency as Beijing prepares to host the Winter Olympics at the start of next month.

Many cities have advised residents to stay put or requiring travellers to report their trips days before their arrival.

Still, some state media outlets are warning against being too harsh, after a county-level government official in Henan province was quoted as saying that some people had ignored the advice to "maliciously return" to their hometown and that they would quarantine and detain such cases.

"It is human nature to return home during the Spring Festival for reunions, so why is it malicious," the official People's Daily newspaper said on its Weibo account.

"Preventing and controlling the epidemic is a big task, but we cannot take a one size fits all approach...(it) must be done in a scientific and legal way, and every desire to return home must be treated compassionately."

Mainland China reported 63 new COVID-19 cases on Jan. 21, down from 73 cases a day earlier, the country's national health authority said on Saturday.

The National Health Commission said in a statement that 23 of the new cases were locally transmitted, the same as a day earlier, and the rest imported.

The number of new asymptomatic cases, which China does not classify as confirmed cases, rose to 43 from 31 a day earlier.

There were no new deaths, leaving the death toll at 4,636.

As of Jan. 21, mainland China had 105,547 confirmed cases.

(Reporting by Winni Zhou and Brenda Goh; Editing by William Mallard) ((winni.zhou@thomsonreuters.com; +86 21 2083 0100; Reuters Messaging: winni.zhou.thomsonreuters.com@reuters.net))