A radical Serbian nationalist is facing defeat at the ballot box after his son began a 'Don't Vote for My Dad' campaign.

Dragomir Antonic, of the Serbian Radical party, is running in local elections in Belgrade on September 19.

But his campaign has suffered a blow after his 26-year-old son Lazar decided to launch his own movement to stop his dad being elected.

Lazar Antonic told Serbian daily newspaper Blic: "I'm preparing posters with the slogan 'Do Not Vote For My Dad Dragomir Antonic' on them just to tell to my father and everyone else that the policies he represents are bad.

"My father and I will still have good relations whatever happens but I want him to understand that his party's radical policies are wrong."

His father said he had no plans to try to stop his son, adding: "No matter what he does he will always be my son."