China's health authorities on Sunday reported 99 new coronavirus cases in the mainland, all but two being imported and marking an increase of more than double from the previous day's figure.

The National Health Commission said in its daily report that overall confirmed cases on the mainland now total 82,052, with no deaths from the disease recorded Saturday.

Of the 97 imported cases recorded in the 24 hours to the end of Saturday, at least 72 were Chinese people who had returned from Russia.

The two domestically transmitted cases were both in Heilongjiang, China's northernmost province which borders Russia, it said.

The number of cases of infection involving returnees from Russia has recently been on the rise in recent days.

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The Chinese Embassy in Moscow announced Wednesday the temporary closure of all land border crossings with Russia. Russia had previously closed its land border to incoming traffic from China in January.

The border city of Suifenhe had by Friday reported a total of 173 imported cases of COVID-19 from Russia, according to the official Xinhua News Agency.

Medical staff and beds have been increased in some areas of Mudanjiang in Heilongjiang Province in preparation for a surge in patients, Xinhua reported.