A Manchester City fan was led away by stewards after making an aeroplane gesture in the direction of Man United fans during the derby on Sunday, according to footage on social media.
The gesture was in reference to the 1958 Munich Air Disaster, in which 23 people died on their way home from a European match, including many members of the Manchester United football team nicknamed the 'Busby Babes'.
The initial clip of the gesture was caught by a Manchester United fan account and posted to X (formerly Twitter), asking the Greater Manchester Police to get involved.
A later video showed the man being led away by a large group of officials in reflective jackets.
Last month, Manchester United marked the 66th anniversary of the disaster, with new co-owner Sir Jim Ratcliffe among those paying their respects to those that lost their lives in the plane crash.
Following the death of Sir Bobby Charlton last October, it was the first anniversary without any living survivors from that devastating day in Munich on 6 February 1958.
Fans also raised a banner in honour of their fallen stars ahead of their Premier League game against West Ham on February 4.
Manchester United manager Erik ten Hag and his West Ham counterpart David Moyes also carried wreaths onto the pitch during the club's memorial for the events of 66 years earlier.
Eight of the Busby Babes and three members of staff were among the 23 people who died as a result of the crash on February 6, 1958 as the plane carrying United back from a European Cup quarter-final against Red Star Belgrade made a third attempt to take off after refuelling at Munich Airport.
Manchester City won the game 3-1, with a Phil Foden brace and Erling Haaland's stoppage time goal turning it around for the hosts after Marcus Rashford opened the scoring with a stunning strike from 25 yards.