Trouble erupted outside Anfield minutes before kick-off in the first leg of the tie on 25 April, with Liverpool fan Sean Cox left in a critical condition after the incident.

UEFA confirmed on Wednesday (AEST) disciplinary proceedings have been opened against both clubs in connection with clashes between supporters.

Liverpool is additionally under investigation for the throwing of objects and setting off of fireworks during the game.

This case will be dealt with by the UEFA Control, Ethics and Disciplinary Body on 1 April.

Jurgen Klopp's Reds face holder Real Madrid in the Champions League final on Sunday in Kiev, having progressed 7-6 on aggregate against Roma.