The head of Israel's coronavirus task force has asked Ukrainian President Volodymyr Zelenskiy to ban an annual pilgrimage in which Hasidic Jews visit the central Ukrainian town of Uman over concerns the site may become a virus hotspot.

Tens of thousands of Hasidic Jews descend on Uman every Jewish New Year to visit the grave of Rabbi Nachman of Breslov, who revived the Hasidic movement and died in 1810. This year, Jewish New Year celebrations run from Sept. 18-20.

The Ukrainian and Israeli governments have already issued a joint statement pleading with pilgrims to cancel their trips, but huge crowds are still planning to fly.

Ronni Gamzu, Israel's lead adviser on the coronavirus, has now sent a letter to Zelenskiy, urging him to take action.

"A gathering of this sort, at such troubled times, is expected to generate mass events of infection of tourists and local Ukrainian residents, turning into a heavy burden on local medical systems, while thousands more are expected to come back to Israel and further spread the virus," Gamzu said in the letter seen by Reuters on Saturday.

"I urge you to enforce a ban on these celebrations this year, as part of the entire global community’s effort to stop this horrific pandemic," he said.

On Friday Israel passed 100,000 reported coronavirus cases. It has recorded 809 COVID-19 deaths among its 9 million population.