Leeds United supporters appeared to sing chants relating to the Munich air disaster at Old Trafford on Saturday.
The travelling contingent had already clashed with Manchester United fans before kick-off as tensions between the two fierce enemies boiled over before the hosts' 5-1 romp.
Their singing was heard by the television microphones at the stadium and reported by journalists from the Manchester Evening News and BBC Sport whilst covering the game.
It came after visiting supporters were also filmed chanting about Red Devils duo Marcus Rashford and Jadon Sancho's penalty misses in the Euro 2020 final.
It soured an occasion which saw the biggest crowd attend a Premier League match since March 2020, as over 75,000 witnessed the Red Devils crush their visitors for the second time since the promotion back to the top flight.
Bruno Fernandes scored a hat-trick and Paul Pogba laid on four assists, levelling the record in a Premier League game.
Ahead of the lunchtime match, Manchester city centre saw violent clashes as the two clubs faced one another with fans in attendance since Leeds gained promotion in 2020.
Following the events, Greater Manchester Police issued a statement which read: "Patrols in city centre made aware of some isolated incidents of disorder at premises in the area.
"We're working closely with those premises to support licensees at early signs of any disorder and negate it as swiftly as possible. No arrests have been made."
On the away concourse, Leeds fanschanted that Sancho and Rashford had "let their country down," having both missed for England in their Euro 2020 final shootout in July.
Chants relating to the Munich air disaster were then heard coming from the away end in the second half.
Old Trafford was already rocking before new signing Raphael Varane was unveiled on the pitch prior to kick-off.
It took United just half an hour to break the deadlock as Fernandes combined with Pogba for the first of two goals that the pair created in a spellbinding display.
Leeds right-back Luke Ayling's stunner just three minutes into the second half levelled the score but Mason Greenwood, two more from their Portuguese talisman and a strike from Fred put the Peacocks out of sight.
It followed United's 6-2 hammering of the Peacocks last December as many tipped Marcelo Bielsa and co to cause an upset against a somewhat depleted Red Devils side.
Rashford and Edinson Cavani were both unavailable, two important components of Solskjaer's side.
Sancho also made his Premier League debut as the Red Devils took a very early lead at the top of the Premier League table.
United travel to Southampton next Sunday as the Leeds host Everton at Elland Road as the stadium gets its first proper taste of Premier League action for 17 years.
