Milorad Dodik was sentenced in February to prison and a ban on holding political offices for six years due to "separatist actions".
Earlier in August, the verdict was upheld in a higher court, but the prison sentence was converted to a fine. At the same time, the federal electoral commission decided to dismiss Dodik in accordance with the verdict.
The referendum concerns the issue of whether the partially self-governing state should accept the electoral commission's decision. It is planned for October 25 and is feared to further weaken the country's central government.
The EU delegation in Bosnia believes that the federal verdict should be respected.
"To put a court ruling to a public vote goes directly against the law and the independence of judicial institutions", the EU delegation writes on X and urges Republika Srpska to de-escalate the situation.
The UK ambassador to Bosnia, Julian Reilly, calls a referendum on the issue "illegal".
