Kick It Out has called for Manchester United fans to stop a "racist" chant about striker Romelu Lukaku.
The 24-year-old arrived from Everton in the summer in a deal that could reach £90million and has quickly become a popular figure among supporters, netting seven goals in as many games.
Lukaku already has a chant in his honour but the song, to the tune of Stone Roses' Made of Stone, references the size of his penis, using a stereotype about black men that has led Kick It Out to call for action.
A spokesperson from the anti-discrimination body said: "Kick It Out is aware of footage of alleged racist chanting by supporters of Manchester United that emerged on Wednesday evening (13 September).
"The lyrics used in the chant are offensive and discriminatory. Racist stereotypes are never acceptable in football or wider society, irrespective of any intention to show support for a player.
"We have contacted Manchester United regarding the issue and will be working closely with them and The FA to ensure that it is addressed swiftly.
"If we receive any reports relating to the discriminatory chant, those will be passed on to the governing body and the perpetrators can expect to face punishment."
Press Association Sport understands Kick It Out have yet to formally contact United about the matter, with the only contact a brief exchange between the body and the club's Equality and Inclusion Officer.
A United spokesman told Press Association Sport: "We are seeking advice from the relevant bodies. Manchester United has a zero tolerance towards all forms of discrimination"
United are seeking advice to determine whether the Lukaku chant is categorised as racism by the letter of the law.
Scott Patterson, a season ticket holder who runs the The Republik of Mancunia blog, called the chant "drivel that belongs in the 1980s".
"Here we have a hugely talented striker, currently the top scorer in the league, yet he's reduced to us celebrating the supposed size of his d***," he posted. " It's a cheap and insulting stereotype that has no place in this day and age."
Greater Manchester Police have confirmed to Press Association Sport they are not currently looking into the matter. There have not been any complaints to GMP as things stand.