Marchers at Sunday’s Pride parade in Belgrade have been warned they are likely to be attacked by anti-gay extremists.
Serbia’s police chief, Ivica Dacic, urged organisers to cancel the event to avoid clashes with a far-right group which has planned a march on the same day.
However, he told Associated Press that police would protect gay marchers and that water cannons were being repaired.
Last year’s Pride march – the first since 2000 – attracted 600 gay and gay-friendly participants and 20,000 protestors, who rioted and threw missiles.
Around 100 people, mainly police, were injured. Cars were burned and shops were looted.
Mr Dacic said this violence at this year’s event could result in buildings being set alight.
The route has not yet been released, for security reasons.
Last month, organisers said they were confident police would protect them.
Organising committee member Goran Miletić said: “I believe that police can secure the gathering so everything would go well. . . The parade is not a threat to security, a bigger threat is when you live with RSD 20,000 (£171) a month.”