The man, who is a well-known member and prominent member of the far-right National Democrats, sustained head injuries in the attack, but was able to leave the hospital after several hours.
Police have classified the incident as attempted murder.
“He was hit in the head with rocks. They also used sticks and clubs. He was also stabbed in the arm,” said police spokesperson C-G Olsson to the TT news agency.
The 35-year-old told police that his attackers were members of the Swedish chapter of the left-wing extremist group Antifascist Action (AFA) and numbered around 20 people.
Otherwise the police have no information about the assailants and no arrests were made as of late Sunday night.