Riot police clashed on Saturday with protesters in Belgrade, where an international Pride march started despite threats from anti-gay groups and an official earlier ban.

Tensions were high in the Serbian capital as protesters hurled stun grenades, stones and flares at a police cordon, which repelled the attack with batons and riot shields.

Hundreds of Pride march supporters, meanwhile, gathered a few miles away in the pouring rain, dancing and singing as their march was held on a shortened route.

“We need justice and freedom,” said Goran Miletic, one of the Pride event organisers.

Serbian police this week banned the parade, over the risk of clashes with far-right activists.

But organisers on Saturday said they received guarantees from Serbian prime minister Ana Brnabic, who is gay, that the event could go ahead.

“Following weeks of intense international pressure, the Serbian prime minister Ana Brnabic has announced that the EuroPride March  can go ahead,” the European Pride Organisers Association said.

“The prime minister said she can guarantee that the streets of Belgrade will be safe this afternoon,” the statement said.

Ms Brnabic said she was proud that during “this entire week, with more then 130 (LGBTQ) events, there wasn’t a one single incident. And that really is the right image of Belgrade and Serbia”.

Several incidents were reported earlier Saturday, with anti-gay activists hurling bottles at police and trying to break through the police cordons. Police said 31 people were detained.

The European Pride Organisers Association chose Serbia’s capital three years ago to host the annual event, hoping it would represent a major breakthrough for a Slavic country that is traditionally conservative and strongly influenced by the Orthodox Church.

Interior minister Aleksandar Vulin warned Saturday that his agency “will not tolerate any violence on the streets of Belgrade and that it will strictly implement the law”.

EU and other western officials, as well as rights groups, had urged populist Serbian president Aleksandar Vucic to allow the Pride march.

But Mr Vucic had said that police could not cope with possible riots by far right groups amid the energy crisis.

Those groups, some of them considered close to Mr Vucic’s nationalist government, were also banned from gathering on Saturday, but they said they would ignore the ruling.

Several legal appeals by march organisers against the ban have been rejected by Serbian authorities.