Officers have today released a CCTV image of a man they wish to speak to following a report the offence at the Manchester Arena just before 11.30pm on Saturday, December 22 2018 following the end of the fight.
In its appeal, the British Transport Police (BTP) said: "A man was seen to approach a woman within the inner bowl of the arena and touch her inappropriately.
"Officers believe the man shown in the CCTV image may have information which could help their investigation. "
Anyone who recognises the man or has more information about the incident is asked to contact BTP by texting 61016 or calling 0800 40 50 40, quoting reference number 710 of December 22.
People can also call Crimestoppers anonymously on 0800 555 111.