MANCHESTER -- Manchester United and Manchester City players were involved in a tunnel bust-up following Sunday's derby, sources have told ESPN FC.
City won the game 2-1 to go 11 points clear in the Premier League title race.
But after the final whistle United players and staff were left unhappy at the way the visitors celebrated, deeming it "disrespectful."
Sources have told ESPN FC that City's celebrations were "very vocal" and accompanied by loud music that could be heard by United players in the home dressing room.
It prompted a confrontation between players and staff from both clubs outside City's dressing room.
It has been confirmed to ESPN FC that there were police officers present in the main tunnel area, although not in the corridor next to the changing rooms. No complaints have been made.
Sources have told ESPN FC that United manager Jose Mourinho was involved in the fracas, which happened in the corridor connecting the home and away dressing rooms, as he walked past City's dressing room to the main tunnel area to fulfil his broadcast media interviews.
BBC Sport and PA Sport reported that Mourinho had milk and water thrown at him and shouted into the away dressing room, while it has also been claimed he was involved in a confrontation with City goalkeeper Ederson.
PA Sport also claimed that City coach Mikel Arteta suffered a cut to the head, with the Guardian adding he "was left with blood pouring down his face."
City did not respond to requests for comment.
In 2004, players from United and Arsenal were involved in a tunnel bust-up at Old Trafford that become known as the "Battle of the Buffet" after Sir Alex Ferguson was hit with a piece of pizza.
United won the game 2-0 to end Arsenal's 49-game unbeaten run. In October, midfielder Cesc Fabregas admitted throwing the pizza at Ferguson.