Fans warned over Yid chants
Tottenham Hotspur fans could be arrested if they use the word Yid at Sunday's home match against London rivals West Ham United.
Scotland Yard said both sets of supporters will be watched by officers and warned them they may be committing an offence if they use the word.
The issue has caused a race row because Spurs fans use the word Yid - a term for Jew which is often considered derogatory - to describe themselves and their north London team.
However, the word is also used by opposing sets of supporters to taunt the Lilywhites.
Prime Minister David Cameron recently weighed into the debate when he told the Jewish Chronicle: "There's a difference between Spurs fans self-describing themselves as Yids and someone calling someone a Yid as an insult.
"You have to be motivated by hate. Hate speech should be prosecuted, but only when it's motivated by hate."
Comedian David Baddiel - a Chelsea fan - has long campaigned for fans to stop using the term.
Scotland Yard said its officers will be taking action to "stamp out" chants featuring the word, and said that while it has historically been perceived by some as acceptable, it causes "harassment, alarm or distress to others".
Chief superintendent Mick Johnson, the match commander on Sunday, said, "This topic has been debated at length but our position is clear, racism and offensive language have no place in football or indeed in society.
"Those supporters who engage in such behaviour should be under no illusion that they may be committing an offence and may be liable to a warning or be arrested."
The London derby game kicks off at 4pm on Sunday.