(AP-ANSA) - PRAGUE - Thousands of Czechs have used the anniversary of their country's 1989 anti-communist Velvet Revolution to rally against Prime Minister Andrej Babis. The protesters gathered Saturday afternoon in front of Prague Castle, the seat of the Czech presidency. They set off on a march to the city's Old Town Square, demanding the resignations of Babis and his ally, President Milos Zeman. Babis has been charged with misusing European Union subsidies for a farm he transferred to family members, including his son, Andrej Babis Jr. The Czech leader denies wrongdoing. His son told Czech news portal Seznam Zpravy this week he was kept in Crimea against his will so he couldn't be questioned in the case. Babis has said his son, who lives in Switzerland, is mentally ill and in Crimea voluntarily. (AP-ANSA).