Heskey was booked for a foul on Croatia's Niko Kovac (l)
Fifa has opened an investigation into allegations that Croatia fans racially abused England striker Emile Heskey during last week's World Cup qualifier.
World's football governing body said it began disciplinary proceedings after receiving an official complaint from the Football Association on Tuesday.
Monkey chants were heard from a section of the Maksimir Stadium when Heskey was booked for fouling Niko Kovac.
Heskey later branded the fans "ignorant people" and said he ignored them.
"You have to let the people above deal with that and I will carry on playing my game," added the Wigan striker.
After consulting Heskey about the chants following the match, an FA spokesman said: "We can confirm that we will be making a report to Fifa about the racist chanting aimed at Emile Heskey by some Croatia fans during the World Cup qualifying game in Zagreb.
"The FA and the England team are determined to do all they can to eradicate any form of racism from football and society."
The FA are right to issue their concerns about it because we thought we'd seen the back of that years ago
Wigan boss Steve Bruce
Croatia were given a small fine during Euro 2008 for racist abuse from their fans during their game against Turkey.
Heskey has been racially abused while on England duty before, in Slovakia in 2002, while Shaun Wright-Phillips and Ashley Cole were subjected to monkey chants in a friendly against Spain in Madrid in 2004.
However, Wigan manager Steve Bruce predicted Heskey would not allow the incident to unsettle him.
"There's no chance it'll affect him," said Bruce. "He's bigger and better than that, and the people that are doing that are morons anyway. He'll just shrug his shoulders and let other people deal with it.
"The FA are right to issue their concerns about it because we thought we'd seen the back of that years ago."
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