Defying the country's constitutional court's ban, Bosnian Serbs say they will hold a referendum on a disputed national holiday in their autonomous region.

The Sept. 25 referendum will ask residents of Bosnia's Republika Srpska region whether they agree the 'statehood' day of the Serb mini-state should remain Jan. 9. The Court ruled the date discriminates against Muslim Bosniaks and Catholic Croats since it falls on a Serb Orthodox Christian holiday.

The court banned the referendum Saturday but Bosnian Serb prime minister Zeljka Cvijanovic said Monday it will be conducted anyway. Western officials have urged Republika Srpska to cancel the vote as it challenges the rule of law and Bosnia's peace agreement but Russia sided with the Serbs, saying they do have the right to hold the referendum.