Thousands of protesters gathered in Prague on Saturday to demand that Prime Minister Andrej Babis step down, with an ongoing government crisis casting a shadow over commemorative events for the Velvet Revolution that began 29 years ago in the Czech Republic.

Holding up European flags, demonstrators chanted "resignation, resignation" in reference to Babis, whom police are investigating on corruption allegations.

In an apparent bid to avoid protesters during Saturday's Velvet Revolution commemorations, Babis laid a bouquet of flowers at a memorial on Prague's National Avenue shortly after midnight. Activists threw the flowers in a trash bin later that morning, news agency CTK reported.

Police replaced the flowers and were investigating the incident as property damage.

Babis, the multi-billionaire founder of the populist ANO Party, is under pressure for a corruption scandal involving subsidies for a luxury spa resort that has since been signed over to a trust. He said on Friday he would "never" step down, responding to another protest attended by thousands on Thursday.

Several organizations called for the Saturday protests "against hate and lies."

The rallies coincided with the Czech Republic's commemoration of the violent suppression of peaceful student protests in Prague on November 17, 1989. The communust government's crackdown unleashed the Velvet Revolution that led to the resignation of the Czechoslovakian government and a transition to democracy.

Since 2000, the occasion has been marked by a public holiday called Struggle for Freedom and Democracy Day. The day also commemorates the closure of Czech-speaking universities by German Nazi occupying forces on November 17, 1939.