Brage are rooted to the bottom of Sweden's second tier with one win and two draws all season and emotions that have been running high among fans boiled over during a recent match.
"One of these so-called fans expressed a direct murder threat during the away game at Degerfors to a Brage player, something which in recent days has been confirmed by several independent sources," the club said on its website.
Club chairman Per Armund Ruth said: "We obviously cannot accept our players being threatened.
"If the player threatened with murder chooses to report it to the police he will do so, something Brage supports. The club has chosen to act with a long ban."