Manchester City midfielder Yaya Toure has described the racial abuse he has been subjected to on social media as "a disgrace".
Police are investigating after Toure was sent racist tweets within hours of reactivating his Twitter account on Monday.
The 31-year-old told BBC Sport: "For me it's a disgrace to be honest. We need to do something to try to tell people those kinds of behaviour have to stop. I want those people to understand what they're doing is wrong."
Toure posted his first message on Twitter in five months after City's derby win over Manchester United at the weekend.
Thanks for all the welcome back tweets and support. Shame about ignorant minority. #StillFocused— Yaya Touré (@YayaToure) November 4, 2014
The Ivory Coast international had previously withdrawn from the social network site to concentrate on the World Cup.
But soon after the posting he began to receive offensive responses, prompting anti-discriminatory body Kick It Out to make an official complaint to police on Monday.
Greater Manchester Police confirmed on Tuesday that complaint had been received. The force have yet to issue a formal statement but a tweet in response to a query about the matter confirmed it was under investigation.
It read: "Thank you - we are aware if (sic) this and are investigating."
The incident comes just over a year after Toure was the subject of racist chants from supporters during a Champions League group game at CSKA Moscow.
Toure was upset by that abuse and even suggested black players could boycott the 2018 World Cup in Russia if the issue was not tackled in that country.
European governing body UEFA punished CSKA for that, ordering them to play their next home game in the competition in a partially closed stadium. Two further offences led to the Khimki Arena being closed to paying spectators when City visited again in this season's competition a fortnight ago.
CSKA will also have no fans present when they play City in the return fixture at the Etihad Stadium on Wednesday.
City manager Manuel Pellegrini is confident the latest issue will not adversely affect Toure on the field.
The Chilean, speaking at his pre-match press conference, said: "I think Yaya is an experienced player. He is always trying to fight against those things but I don't think he will have any problem about that, to play in the way he knows (how) to do it.
"I read the news about what happened but I think the people in charge will do the right things."
Kick It Out expressed concern immediately after learning of the abuse Toure had received via Twitter.
A statement from Kick It Out read: "We received complaints about two separate tweets of a racist nature aimed at Yaya Toure yesterday evening.
"We have informed the police via True Vision, the online reporting facility, and have also alerted Twitter.
"Yaya Toure has been back on Twitter for a matter of hours and he has already received abuse of an appalling nature.
"We are disturbed by the fact that someone can be treated this way. It makes footballers start to question why they should use these platforms. We are offering Yaya Toure our full support."
Toure added that he does not understand the reason for such hateful abuse.
Speaking to BBC World Service, he added: "To have such aggression in sport, I can't understand that. That's why I've been trying to fight it.
"Football doesn't have a colour. We're just people from all over the world trying to enjoy the game.
"I never see this in rugby, I never see that in tennis or anything else. I don't know where it's coming from."
Asked if he was hurt by the abuse, Toure said: "To be honest with you, no, because I've been attacked like that for many years. I will never stop telling them they are wrong and have to change."