Liverpool are looking into claims youth team player Jordan Williams mocked the Munich air disaster during last night's Europa League match at Manchester United.

Press Association Sport understands the club are aware of the allegations but have not commented publicly.

A tweet sent from the 20-year-old academy graduate's Twitter account, responding to a video of Liverpool fans celebrating inside Old Trafford after a 1-1 draw sent their side through 3-1 on aggregate, depicted an aeroplane emoji and pair of hands clapping.

In 1958 eight United players were among 23 who died in a crash in snowy conditions at Munich Airport and some Liverpool fans have been known to taunt their arch-rivals with a song and aeroplane gestures.

The tweet was quickly deleted and Williams later apologised, claiming his account had been compromised.

"My Twitter has been hacked, I would never put anything like that to offend anyone, sorry about this," he wrote.

Manchester United 1 Liverpool 1 player ratings Show all 24 1 /24 Manchester United 1 Liverpool 1 player ratings Manchester United 1 Liverpool 1 player ratings David de Gea – 7 out of 10 Could he potentially have stood up better for Coutinho’s goal? Maybe but once again, it was his saves and stops which kept it from getting embarrassing. Manchester United 1 Liverpool 1 player ratings Guillermo Varela – 5 out of 10 Tenacity, dynamism but full of defensive lapses. He is like a proto-Rafael and a player that supporters should grow to love, but one that has a lot to learn. Manchester United 1 Liverpool 1 player ratings Chris Smalling – 6 out of 10 Faced little threat in the first half with the onus on his attacking team-mates but looked troubled as the game went on, especially after Origi’s introduction. 2016 Liverpool FC Manchester United 1 Liverpool 1 player ratings Daley Blind – 7 out of 10 Like his defensive partner, benefited from his team needing to attack. Largely solid, distributed well and coped well with Liverpool’s pace in behind. 2016 Manchester United FC Manchester United 1 Liverpool 1 player ratings Marcos Rojo – 6 out of 10 Looked more comfortable with his offensive duties tonight and offered excellent support to Martial, compounding Clyne’s misery. Defensively, still suspect and often switched off. 2016 Manchester United FC Manchester United 1 Liverpool 1 player ratings Michael Carrick – 6 out of 10 Far more comfortable at the base of midfield than the makeshift-sweeper role he took up at Anfield but, judging by his fitness, will not operate at this level much longer. 2016 Manchester United FC Manchester United 1 Liverpool 1 player ratings Marouane Fellaini – 4 out of 10 The most unpopular man in the ground. The jeers may be undeserved but so is his starting place, and he should not have stayed on after his elbow on Lovren. 2016 Manchester United FC Manchester United 1 Liverpool 1 player ratings Jesse Lingard – 5 out of 10 The young winger will feel he could have done better with an early header on goal. Interchanged with the rest of the forward line but offered nothing decisive. 2016 Manchester United FC Manchester United 1 Liverpool 1 player ratings Juan Mata – 5 out of 10 Loose passes early on gave the impression this would be one of the Spaniard’s poorer evenings and a scuffed volley minutes later confirmed as much. GETTY IMAGES Manchester United 1 Liverpool 1 player ratings Anthony Martial – 8 out of 10 United’s best attacking outlet. He had the beating of his man from the first minute to the last but he cannot do it all himself 2016 Manchester United FC Manchester United 1 Liverpool 1 player ratings Marcus Rashford – 6 out of 10 Seven consecutive starts told on the youngster’s legs. He often lacked the zip required to beat the last man but was adventurous nonetheless. Manchester United 1 Liverpool 1 player ratings BEST OFF THE BENCH: Bastian Schweinsteiger – 5 out of 10 The German, who looks ‘well wintered’ after his injury break, scuffed a shot and made a silly tackle. Influential on Sunday, anything but here. Getty Manchester United 1 Liverpool 1 player ratings Simon Mignolet – 6 out of 10 Denied Lingard acrobatically in the first-half when a simpler save may do. The Belgian largely maintained the uncharacteristic composure he’s shown in recent weeks. 2016 Liverpool FC Manchester United 1 Liverpool 1 player ratings James Milner – 6 out of 10 Filling in at left-back at times seemed a big ask, especially against the adventurous Varela in the first-half, but he slowly grew into the role. Manchester United 1 Liverpool 1 player ratings Dejan Lovren – 7 out of 10 Another to maintain the improved form he’s shown recently, give or take a few shaky moments. a new confidence under Klopp. 2016 Manchester United FC Manchester United 1 Liverpool 1 player ratings Mamadou Sakho – 7 out of 10 Cumbersome, inelegant but at least he can pass a ball. Much of Liverpool’s best attacking play came out of the back through the Frenchman. 2016 Manchester United FC Manchester United 1 Liverpool 1 player ratings Nathaniel Clyne – 4 out of 10 Since joining last summer, the right back has been solid, week in and week out. Tonight was his off-night and Martial made the most of it. Manchester United 1 Liverpool 1 player ratings Philippe Coutinho – 7 out of 10 The Brazilian looked out-of-sorts until his sublime goal, which will go down as one of Liverpool’s best on this ground. Ultimately, a tie-winning performance. 2016 Liverpool FC Manchester United 1 Liverpool 1 player ratings Roberto Firmino – 5 out of 10 Failed to carry his excellent form into this encounter. Instead, he reminded us that he easily drifts out of games and still much to prove. 2016 Getty Images Manchester United 1 Liverpool 1 player ratings Jordan Henderson - 5 out of 10 Liverpool’s captain failed to impose himself on the occasion. The one moment he did, he earned a clear cut chance but could only fire over. 2016 Liverpool FC Manchester United 1 Liverpool 1 player ratings Roberto Firmino – 5 out of 10 Failed to carry his excellent form into this encounter. Instead, he reminded us that he easily drifts out of games and still much to prove. Manchester United 1 Liverpool 1 player ratings Daniel Sturridge – 5 out of 10 Liverpool will be glad they learned how to cope without him during his time out injured. He’s been in a rut since returning and this was no better. Manchester United 1 Liverpool 1 player ratings Adam Lallana – 5 out of 10 A peripheral figure for much of the match and will be disappointed not to have built on the dynamism he showed at Anfield. 2016 Manchester United FC Manchester United 1 Liverpool 1 player ratings BEST OFF THE BENCH: Divock Origi – 7 out of 10 An intelligent substitution by Klopp. His pace, strength and drive pushed Liverpool ten yards up the field, keeping United at bay in the closing stages.

There was a distasteful atmosphere surrounding the whole match last night with Liverpool supporters arriving for the last-16 second leg tie greeted with a banner with the word 'Murderers' and the date of the Hillsborough disaster - where 96 Liverpool fans died - tied to a bridge over the M602 in Salford.