The abuse of Emmanuel Adebayor in Tottenham's Champions League defeat at Real Madrid had "racial undertones", says anti-racism group Kick It Out.
Spurs fiercely denied offensive chants aimed at the striker were racist.
But Kick It Out chairman Lord Ouseley said the words "Your dad washes elephants," were a slight on his African heritage.
"It's not racist but it is abusive and it has racial undertones to it," Lord Ouseley told BBC Radio 5 live.
"Clearly, Adebayor and his colleagues playing for Real Madrid found it offensive.
"If you asked Spurs's black players if it was something they would find inoffensive if it was sung about them, I think you wouldn't find a different result.
"If they sing it next week in the return game, there'll be problems. Because I'm sure the black fans of Spurs are not going to be singing that song."
Uefa said there was "nothing in the delegate's report" from Tuesday night's quarter-final first leg that would trigger an investigation from European football's governing body.
But Lord Ouseley said: "We know that Football Against Racism in Europe (Fare), which is the European version of the Kick It Out campaign, are taking up the matter with Uefa. So we wait and see."
Kick It Out chairman
“No-one is saying this song is overtly racist. But, clearly it is offensive and it's about setting standards”
A club whose supporters are deemed guilty of racist chanting can be fined a minimum of £20,000.
Spurs face Madrid at White Hart Lane for the return leg on Wednesday.
Adebayor has scored 10 goals in 13 games against the Londoners and his double in the Bernabeu set up a comfortable victory for the Spaniards on Tuesday.
Tottenham have admitted the abuse of former Arsenal and Togo striker Adebayor was offensive but a spokesman said: "The chant referred to has been previously discussed with the Crown Prosecution Service, who do not consider it racist.
"We shall continue to remind our fans that we do not tolerate any form of obscene or abusive chanting."
Lord Ouseley added: "Clubs say, 'We don't tolerate such things', but yet it's still happening. No-one is saying this song is overtly racist. But, clearly it is offensive and it's about setting standards.
"If we're not careful, if we relax, then these things become prevalent again."
Adebayor, who scored twice in Spurs' 4-0 defeat on Tuesday and is on loan from Manchester City, said the fight against racism was ongoing but conceded "we can't do anything to stop it".
He said: "Big players better than me have tried to stop that, but it's not easy at all. Racist? We have done everything we can to show the red card to racism. But people are still into it, that's part of life.
"Coming from Africa, I'm just very happy, playing football is like a dream that comes true. Racists are always there and we can't do anything to stop it."