Serbian police were deployed in the capital Belgrade Saturday to enforce a ban on a Gay Pride parade for the third year running, an act the EU said could undermine Serbia's chances of joining the bloc
Hundreds of police in full anti-riot gear surrounded a park in downtown Belgrade where the parade was due to take place, as well as main buildings and key crossroads.
On Friday Serbian Prime Minister Ivica Dacic announced the parade would have to be cancelled after far-right groups threatened protests.
The European Union said it expected Serbia to probe the threats of violence and "take necessary measures" to prevent them in future.
But it said the decision to ban the parade was regrettable. "It is a missed opportunity to show respect for fundamental rights," EU Enlargement Commissioner Stefan Fuele said in a statement.
"I am committed to seek from candidate countries that they fully embrace values such as freedom of assembly and freedom of expression that are amongst the core foundations on which the European Union project is built," Fuele said.
"This is particularly important in the context of Serbia's accession negotiations," he added.
Serbia, a candidate for EU membership since mid-2012, is expected to start accession talks with Brussels in January, but human rights activists have already warned it could be hampered by the ban of the Gay Pride parade.
Later on Saturday, the organisers said they would lodge an appeal against the ban.
"We will of course appeal to the Constitutional Court as well as to the European Court of Human Rights in Strasbourg," Goran Miletic of the organisers told a press conference.
"But the question is what impact that will have" considering that the constitutional court had found that the bans on the parade in the previous two years were in breach of Serbia's constitution and nothing changed, he said.
A number of foreign officials, including Swedish Minister for European Union Affairs Birgitta Ohlsson and Dutch MP in the European Parliament Marije Cornelissen, joined the press conference in a sign of support.
They spared no words to criticise the Serbian authorities for failing to deal with violent groups that threatened the parade.
"I see up to now no concerted effort to combat these groups and make Serbia a safe place for everybody. I'd say this is a total failure of the government. If they cannot keep these groups in check it basically means that... they have no proper rule of law," Cornelissen said.
Following the news of the ban a few hundred people gathered outside the Serbian government building late Friday carrying a large banner that read: "This is pride".
Escorted by dozens of police in anti-riot gear, the group then marched through downtown Belgrade to the Serbian parliament building, holding a huge rainbow-coloured flag.
The last Gay Pride parade in Serbia in 2010 ended in violence. Over 150 people were injured, mostly police, and the damage estimated was more than one million euros ($1.35 million).