Bulgarian fans have been accused of aiming monkey chants at Denmark's black defender Patrick Mtiliga during Friday's 1-1 World Cup draw between the two sides.
The Bulgarian sports website www.sportal.bg. claimed that the cries started as soon as Mtiliga, whose father is Tanzanian, came on as a 54th-minute substitute.
"I didn't hear anything during the match. I only heard about it when I got back to the dressing room," said Mtiliga.
"It's disgusting that such things are still going on. I have been told that the FIFA delegate at the match has noted the incident and that measures will be taken," added Mtiliga, who plays his club football for Danish champions Nordsjaelland.
Friday's incidents came just a month after Armenia players complained of chants of "gypsies" being aimed at them during a World Cup qualifier which Bulgaria won 1-0.
Last year, the Bulgarian football federation was fined 40,000 euros by UEFA after spectators racially abused a number of black England players in a Euro 2012 qualifier.