UEFA President Michel Platini has written to all 53 European soccer associations to urge them to combat violence.
Platini, who was elected president of European soccer's governing body in January, has been trying to reduce violence on the field and in the stands since he took office. Last week, the Frenchman met with government and police experts from around the continent to ask for help from all European states.
"Our game is under serious threat - from violence," Platini wrote. "Violence on the field, in the stands and outside stadiums is poisoning football."
The letter, published Thursday on UEFA's Web site, did not single out any particular incident. Instead, Platini referred to problems "from all corners of Europe" that were becoming increasingly commonplace.
Platini urged soccer authorities across the continent to adopt a policy of "zero tolerance" against violence and racism.
"The behavior of certain players and team officials puts football to shame," Platini wrote. "Violence, abuse and gratuitous insults have become the order of the day in football. This has to stop."
Since the 2006 World Cup, soccer has seen a series of violent episodes, including riots in France, the death of an Italian policeman at a match in February, and an ugly brawl at a European Champions League match between Inter Milan and Valencia in March.