The English FA is investigating the racist abuse directed at Arsenal's bench by a Leeds fan during Saturday's Premier League game.
Referee Andre Marriner halted play in the 34th minute to consult with match officials after the incident had been reported and Arsenal boss Mikel Arteta confirmed after the game that some unnamed substitutes had been targeted.
Leeds condemned the abuse following their 4-1 defeat and said in a statement that one arrest had been made in relation to the incident.
The West Yorkshire club said: "Leeds United can confirm that an investigation into claims of racism during the first half of our game with Arsenal today is underway, and that one arrest has been made in connection to the allegation.
"Racism will not be tolerated at Leeds United and any supporter found to be using racist language will be subject to a lifetime ban for all Leeds United games."
The Premier League, which announced new enhanced anti-discrimination protocols at the start of the season, including permanent bans for anybody found guilty of discriminatory abuse, is understood to be supporting the investigation
