A gay pride march in a coastal town in Croatia ended in violence on Saturday when a stone-throwing mob attacked marchers.

The march, in the town of Split, attracted 200 LGBT people and their allies, but police said thousands of people lined the streets in protest.

Extremists then began throwing bottles, stones and firecrackers at the marchers, Associated Press reports. Police had to use barriers to separate the two sides, although gay campaigners said they were not protected properly.

It is not clear how many people were injured, although Amnesty International cited reports which said five people needed treatment, including one for a head injury.

More than 100 people were arrested.

The violence came just one day after Croatia was given the go-ahead to join the European Union.

Nicola Duckworth, Amnesty International’s director for Europe and Central Asia, accused police of not protecting marchers.

She said: “The authorities must hold an immediate investigation into what happened. The police have to make absolutely clear that discriminatory violence is a criminal offence and will not be tolerated.

“The Croatian authorities need to act to stop this happening in future. A first step would be for all political leaders to state unequivocally that everyone has the right to peacefully demonstrate and express their identity.”