Croatia and Russia could be deducted points in the World Cup, after Fifa confirmed it was opening an investigation into antisemitic actions by their supporters.
Football's world governing body said it will start disciplinary proceedings against over supporters displaying neo-Nazi banners during Croatia's and Russia's opening matches.
In Croatia's game against Brazil, fans held up a banner showing the coat of arms of the country's fascist regime which collaborated with the Nazis during the Second World War.
They were reported to Fifa by the anti-discrimination group, the Fare Network.
Speaking to the Telegraph, Fare executive director Piara Power said: "It seems that some fans of some countries will take their hatred halfway around the world. These images need to be acted on urgently."
Mr Power, who was a former director of UK-based organisation, Kick it Out, said a zero-tolerance approach was needed.
"Fifa has some strong regulations in place and we hope they use them. Zero tolerance is the approach set out. It is what is required here," he said.
Meanwhile, Brazil and Mexico could also face disciplinary action by Fifa over homophobic chants from their supporters during Tuesday's game between the two nations.
Mexico fans are also accused of singing a homophobic chant in their opening match against Cameroon.