Three people were injured Sunday at a peaceful anti-Nazi demonstration outside Stockholm following an attack by a group of counter-demonstrators, Stockholm's police said.

"An authorised demonstration was attacked by some 30 people, who even attacked the police onsite," Stockholm police spokesman Kjell Lindgren said.

"Two people were injured and taken to hospital and a policeman was also taken to hospital."

Between 500 and 800 demonstrators, according to the organisers, had gathered in Stockholm's southern suburb of Kaerrtorp to protest against the spread of racism in their neighbourhood.

"I was giving a speech when the Nazis came and started throwing bottles and crackers at the families," Students Against Racism member Enzo Nahuel told Swedish news agency TT.

Two people were arrested in the early afternoon, and around 30 were awaiting questioning by the police.

The demonstration was organised by the Line 17 Network, an umbrella civic organisation that had warned over the increasing presence of Nazi propaganda in the area since last summer.