Manchester United are "seeking advice" over how to deal with a supporters' song for Romelu Lukaku deemed to include racist stereotypes by anti-discriminatory group Kick It Out.
The Premier League giants have been urged to crack down on the song which makes reference to the Belgian striker's manhood.
Lukaku has made an immediate impact at Old Trafford, having scored seven goals in seven games, yet one of the songs chanted by United fans in tribute has prompted Kick It Out to call for swift action.
"Kick It Out is aware of the footage of the alleged racist chanting by supporters of Manchester United that emerged on Wednesday evening [13 September]," said a Kick It Out statement.
"The lyrics used in the chant are offensive and discriminatory. Racist stereotypes are never acceptable in football or wider society, irrespective support for a player.
"We have contacted Manchester United and will be working with closely with them and the FA to ensure that the issue is addressed swiftly. The perpetrators can expect to face punishment."
Chelsea moved swiftly to quash a song for new signing Alvaro Morata earlier this season that contained anti-semitic lyrics, by announcing anyone found singing it at Stamford Bridge could be prosecuted.
United has said they are seeking advice "from the relevant bodies," before adding that they had "a zero tolerance policy towards all forms of discrimination".