(AP) Serbia's first ever openly gay prime minister joined several hundred gay activists Sunday at a pride event in Belgrade amid tight security in the conservative Balkan country.

Holding rainbow flags, balloons and a banner reading "For change," pride participants gathered in Belgrade, the Serbian capital, before setting off on a march through the city. Many approached Prime Minister Ana Brnabic, greeting her and taking selfies.

"My message here today is that the government respects all citizens," Brnabic told reporters. "We want to send a signal that diversity makes our society stronger."

Serbian riot police cordoned off the city center with metal fences early Sunday to prevent possible clashes with extremist groups opposed to the pride gathering.

Brnabic was elected earlier this year amid Serbia's efforts to improve its image as it moves toward European Union membership. Gay activists in Serbia have hailed Brnabic's appointment as an important step in their struggle for gay rights, but say much more still needs to be done.

Serbia's embattled gays have faced widespread harassment and violence from extremists. The first ever pride march in 2001 was marred with violence, and more than 100 people were injured during a gay pride event in 2010 when police clashed with right-wing groups and soccer hooligans. Several pride events had been banned before marches resumed in 2014.

On Sunday, hundreds of riot police fenced off downtown Belgrade as helicopters flew over. Right-wing activists gathered in a central area with banners but no incidents were reported.

Brnabic attended the pride march last year when she was public administration minister in the previous government of now-President Aleksandar Vucic. A former ultranationalist who now says he is a pro-EU reformer, Vucic has declined invitations to attend the pride march.