Thousands of anti-riot policemen have been deployed in downtown Belgrade in an effort to protect a gay pride march that has faced threats from extremists.

Water cannons, armored vehicles and shielded policemen on Sunday blocked all traffic on the planned route of the march as Serbia tries to show it respects human rights of all of its citizens as it seeks European Union membership.

Officials have allowed Sunday's event despite fears of a repeat of the violence in 2010 when right-wing groups attacked a pride march in Belgrade, triggering clashes with police that left more than 100 people injured. Authorities in the conservative Balkan country banned gay rights marches planned for the following three years, citing security reasons.

On Saturday, thousands of extremists protested in Belgrade against the march.