Hearts' PA system was 'hacked', leading to The Sash being played at Tynecastle during the FOH open day.
Footage emerged on social media showing the well-known loyalist tune blaring as fans toured the stadium.
It happened during the Foundation open day event where Hearts fans were given unprecedented access to the Tynecastle facilities
But there appeared to be an interruption as video footage showed the song playing loudly over the PA system.
The clip was met with outrage from fans with many calling for the club to investigate.
Football Scotland report that the footage is genuine with the Scottish Premiership club confirming the sound on the video was not dubbed.
And it's said that their PA system was hijacked by an audio anarchist.
The Edinburgh club are likely to launch an internal investigation into the incident to establish how it was able to take place.
Hearts face Dundee United on Saturday after their defeat to Aberdeen at the weekend.
