Liverpool fans jeered the national anthem in front of Prince William at Wembley.
They received widespread criticism on social media as the Football Association were launching a new mental health campaign before kick-off at the Community Shield.
Liverpool fans have often booed the national anthem in the past but this was particularly loud ahead of the showpiece and the fact it was done in front of the Duke of Cambridge is likely to have gone down badly with the FA and the new campaign.
Prince William has supported the Heads Up campaign and said: “We all need to take care of our everyday mental fitness, and provide support to one another when we face setbacks so we can be match fit for whatever lies ahead.”
Football has got behind various campaigns on mental health and, as it has become such an issue in the game, it will be seen as an own goal by Liverpool fans.
After the game, Liverpool boss Jurgen Klopp was asked whether he thought it was disrespectful but claimed it was more to do with historical grievances.
Klopp said: “I don’t think I’m the right person (to ask), I know a bit about the history but it’s not for me to judge.
“I know the Liverpool supporters are respectful. If they give that sign the reason might be a bit in the past. But I’ve nothing else to say about that.”
Meanwhile, British transport police are also investigating images and videos from violent clashes between Liverpool and Manchester City fans on the London Underground on the Tube.