Atletico Madrid say that the club will expel the "Frente Atletico" from the Estadio Vicente Calderon, having received evidence from police that members of the radical group were involved in the death of Deportivo La Coruna ultra Francisco Javier Romero Taboada last weekend.
The 43-year-old member of the "Riazor Blues" group died as the result of injuries sustained during a pre-organised street fight -- with the autopsy finding he had most likely been hit with an iron bar.
Spain's political and football authorities have all condemned the events, with sports minister Miguel Cardenal and La Liga president Javier Tebas calling for an end to the links between clubs and all ultras groups.
Eleven people have now died in separate incidents around La Liga matches over the last 32 years -- including a Real Sociedad fan who was attacked and killed outside the Calderon in 1998.
Atletico figures had at first claimed that such episodes were a broader societal problem, and not directly the responsibility of the club.
Immediately after Sunday's game club president Antonio Cerezo claimed the incident had "nothing to do with football," and chief executive Miguel Angel Gil argued that the "Frente Atletico" ultras group should not collectively be punished for the actions of some of its members.
Speaking on Tuesday, coach Diego Simeone said the ultimate responsibility for ending violent clashes between "ultras" groups lay with politicians, not those who work in football.
However, mounting public and media pressure has apparently led Atletico to reconsider its stance, and a club statement released on Tuesday afternoon said that after learning club members had been involved in the incident it had decided to end any association with the ultras group.
"Today, the club received the official police report on the game, in which the facts are described along with the names of people identified and/or detained by the police for having directly or indirectly participated in the mass brawl," the statement said.
"Among those identified are 15 people who say they are Atletico Madrid fans, eight of which are club socios [members]. All the members have been expelled without the possibility of returning in future.
"Also, as the police have proven that the 'Frente Atletico' was involved in the incidents in an organised and planned manner, the club has taken the decision to expel this group, as of from today, and to end all relations with it. The club will do everything it can to stop the exhibition of any banners or other distinctive elements of this group inside the Estadio Vicente Calderon."
Meanwhile, Deportivo have also released a statement saying that it wants a full house at next Saturday's La Liga fixture at home to Malaga to participate in a mass protest against violence in football.
"We want to promote from Deportivo that next Saturday at Riazor becomes a mass protest with a sporting spirit," the statement said. "To do that, all citizens who want to show their rejection of violence in football can show that by acquiring tickets at the symbolic price of one euro to fill the stadium and show everyone the true disposition of this unique fanbase. It will also be a gesture to ask for respect for the magnificent fans of Deportivo."
Depor appear to not be planning to take long-term measures against the "Riazor Blues," however the area of the ground where this group usually congregate will be closed for two games.
"The board of Real Club Deportivo de La Coruna, having analysed all the information available regarding the events of last Sunday in Madrid, has decided on a series of measures to lead a movement in favour of football 100 percent free of verbal and physical violence," their statement said.
"The first measure is the closure, provisional and symbolic, of the 'Maraton Inferior' area of the ground for the next two games at Riazor - tomorrow [Copa del Rey last 32 first leg, also against Malaga] and on Saturday. We know this will affect many fans who have nothing to do with this stain on football, but these will be relocated elsewhere in the stadium."
Miguel Angel Gil Marin chief executive told Deportes Cuatro: "I can't dissolve [the group], but I can expel them. All those who don't understand the values associated with this sport, they can sit out."