Hibernian say they will do “everything” they can to identify a supporter who appeared to racially abuse Hearts’ Clevid Dikamona during Saturday’s Edinburgh derby at Easter Road.
Television pictures from the match at Easter Road caught a home supporter apparently shouting at the Frenchman.
Images of the incident have spread on social media, with Hibs describing it as “unacceptable”.
Hearts went on to win the game 1-0 thanks to an Olly Lee strike.
“The club will do everything we can to identify the individual concerned and we will take the appropriate action. It’s unacceptable,” said a club spokesman.
The previous meeting between the sides was marred in controversy after Hibernian manager Neil Lennon was struck with a coin in a bad-tempered night at Tynecastle.
A man was later charged with assaulting an assistant referee, while a punch was aimed at Hearts goalkeeper Zdenek Zlamal.
On the eve of Saturday’s match, Hibs chief executive Leeann Dempster and Hearts owner Ann Budge told BBC Scotland they believed they were “winning” in the battle against anti-social behaviour.
“Despite what happened in the last game I do actually think we are winning,” said Budge.
Source BBC News