Liverpool progressed to the quarter-finals 3-1 on aggregate after Philippe Coutinho cancelled out Anthony Martial's penalty opener to secure a 1-1 draw in the second leg but the tie was marred by some unruly fan behaviour during both games.
A handful of Liverpool fans sitting in the top tier of the East Stand among the home supporters unfurled a banner in the dying minutes of the game, sparking clashes in which punches were thrown and a seat hurled.
Liverpool fans in the lower tier of the stand began chanting “Munich” in a reference to the 1958 air disaster while the fighting progressed.
Police and stewards were forced to form a human shield to separate the two sets of supporters and Greater Manchester Police confirmed making five arrests and said they were investigating a “handful of concerning incidents”.
“The policing operation for the Manchester United v Liverpool match has now come to an end and towards the end of the game there were a handful of concerning incidents which are currently being investigated,” Superintendent Jim Liggett, match commander for the tie, told British media.
“We have made a total of five arrests.”
Fans also lit flares shortly after Coutinho equalised at the end of the first half.
In the first-leg at Anfield, Liverpool's 2-0 victory was marred by a section of United supporters chanting about the Hillsborough stadium disaster, when 96 Liverpool fans died following a crush of bodies at an FA Cup semi-final against Nottingham Forest in 1989.
United avoided a Uefa sanction as the match officials did not mention the incident in their match report. – Reuters
Original source: United, Liverpool face Uefa sanctions