Leeds have opened an internal investigation after video footage of a fan making alleged racist gestures was circulated on social media.
The video was posted by QPR supporters after their side's midweek win against Leeds at Loftus Road.
"The club are aware of a video circulating on social media from our Sky Bet Championship fixture against QPR on Tuesday evening," Leeds said in a statement.
"An investigation is now underway to identify those involved.
"Racism will absolutely not be tolerated by Leeds United and anyone found to be racially abusive will be banned from attending all games indefinitely."
Leeds missed out on a return to the top of the table after losing the game 1-0, while QPR halted a run of seven straight league defeats.