The Football Association have launched an investigation into the ugly tunnel row that marred the Manchester derby at Old Trafford on Sunday during which Manchester City coach Mikel Arteta suffered a cut head and milk and water was thrown towards Jose Mourinho.

A huge melee broke out after Manchester United reacted with displeasure to what they felt were excessive celebrations from City’s players and staff after their 2-1 win moved them 11 points clear at the top of the Premier League table.

“The FA have sought observations from both clubs in relation to an incident which occurred following yesterday’s game,” the FA said.

United and City have been given until 6pm on Wednesday to respond to the FA, after which the governing body will decide whether the situation demands further investigation and potential sanctions for both clubs.

Although the fracas broke out in a narrow corridor outside City’s dressing room, which is opposite the referee’s room, it is understood that referee Michael Oliver did not witness the row and has made no reference to it in his report.

Greater Manchester Police are not currently investigating the matter, even though one of their officers stationed in the Old Trafford tunnel was forced to intervene to help stewards diffuse the skirmishes.