The region has the European Union's lowest vaccination rates, an unwelcome distinction in which both political and economic factors play a role, and deadlier variants of the virus are spreading there fast.

Supporters of Prime Minister Viktor Orban, 58, are to hold a march across central Budapest on Saturday to mark the 65th anniversary of Hungary's failed uprising against Soviet rule.

Orban's rallies generally attract tens of thousands and the event can serve as a show of force for the nationalist, who is contesting a Spring parliamentary vote in which he will face a united opposition for the first time since 2010.

The joint opposition also plans a rally of its own, its first major mass event since small-town mayor Peter Marki-Zay stunned leftist frontrunner Klara Dobrev in a primary run-off last week to become Orban's challenger next year.

"Due to the rapid spread of the aggressive coronavirus variant that can also cause severe side-effects, the Hungarian Medical Chamber is calling on our compatriots that only those with immunity certificates should attend mass events and they should also wear masks," the chamber said in a statement.

Asked whether Hungary, which has seen a steady increase in new cases over the past weeks, was planning to make mask wearing in public places mandatory again, Orban's chief of staff, Gergely Gulyas, said Hungarians were old enough to decide whether they should be wearing them.

On Friday the country registered 2,548 new cases, bringing their total number to 843,825 with 30,492 deaths. About 5.7 million people, or slightly over half of the population, has been fully vaccinated against COVID-19.