Manchester United fielded a complaint from Kick It Out on Monday night about a terrace chant a small section of supporters sang about Romelu Lukaku's manhood.
The anti-racism organisation wrote to United after footage emerged of the song, with lyrics describing how well endowed the striker is, during victories over Basle and Everton at Old Trafford.
Kick It Out deem elements of the song - to the tune of Made of Stone by The Stone Roses - 'offensive and discriminatory'.
A spokesman told The Times: "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 it is addressed swiftly."
The Daily Mail reports that United will seek advice on the situation, with club sources stressing they have a zero tolerance to racism.
The development comes a week after Alvaro Morata implored Chelsea fans to stop a chant about him which carried anti-Semitic messages.
Chelsea owner Roman Abramovich is the chairman of the Federation of Jewish Communities of Russia and the Premier League champions moved swiftly to make their feelings known after the game.
A Chelsea spokesman said: "The club and the players appreciate the fans passionate support away from home, of course, but the language in that song is not acceptable at all.
"I've spoken to Alvaro about it. Alvaro does not want to be connected with that particular song in any way and both the player and club request the supporters stop singing it with immediate effect."