Erik ten Hag said: “The rivalry between Manchester United and Liverpool is one of the greatest in world football. We all love the passion of the fans when our teams meet, but there are lines that should not be crossed.
“It is unacceptable to use the loss of life – in relation to any tragedy – to score points, and it is time for it to stop. Those responsible tarnish not only the reputation of our clubs but also, importantly, the reputation of themselves, the fans, and our great cities.
“On behalf of myself, our players, and our staff, we ask our fans to focus on supporting the team on Sunday, and representing our club in the right way.”
Jurgen Klopp added: “One of the main reasons why the rivalry between Liverpool and Manchester United is so special is that it is so intense and no one should ever want to change this.
“But at the same time, when the rivalry becomes too intense it can go to places that are not good for anyone and we do not need this.
“We do want the noise; we do want the occasion to be partisan and we do want the atmosphere to be electric. What we do not want is anything that goes beyond this and this applies especially to the kind of chants that have no place in football. If we can keep the passion and lose the poison, it will be so much better for everyone.”
Liverpool and Man United meet on Sunday but recent matches have been marred by groups of fans singing and mocking the other club’s tragedies including Hillsborough, Heysel and Munich. United won the last meeting 2-1 in August.