A Chelsea supporter was arrested for allegedly racially abusing Tottenham forward Heung-Min Son during Sunday's London derby.
The game at the Tottenham Hotspur Stadium, which Chelsea won 2-0, was stopped during the second half by referee Anthony Taylor for a separate allegation of racist abuse aimed at Chelsea defender Antonio Rudiger.
While Spurs' investigation into the incident - which has included the study of hours of CCTV footage - has so far proved "inconclusive", it has now emerged that an away fan was ejected and arrested during the Premier League clash.
The Metropolitan Police, who are also investigating the alleged abuse of Rudiger, confirmed that a supporter was arrested after allegedly committing a racially aggravated public order offence, which is understood to have been aimed at Spurs' South Korean forward Son.
It remains unclear exactly when the incident that led to the arrest occurred, during the occasionally bad-tempered game, which saw Son sent off following a VAR review for kicking out at Rudiger after 62 minutes.
It was just moments later that Rudiger reported his alleged abuse to Taylor, after which the game was halted, before three separate announcements were made over the public address system warning that racist behaviour among spectators was interfering with the game.
Chelsea: We will take strongest possible action
Chelsea said in a statement on Monday evening about the Son incident: "We are aware of an alleged racist incident involving a Chelsea supporter at yesterday's match.
"Chelsea Football Club will not tolerate any form of racism, nor is there a place at this club for anyone who is found to have engaged in such behaviour.
"If a season ticket holder or member is involved, we will take the strongest possible action against them including bans.
"We will also support any potential criminal proceedings by the relevant authorities."
Premier League: We will not tolerate discrimination
Earlier on Monday evening, the Premier League released a statement which read: "The Premier League and our clubs will not tolerate discrimination in any form.
"If people are found to have racially abused Chelsea's Antonio Rudiger or Tottenham Hotspur's Heung-Min Son, they deserve to be punished.
"We will support Tottenham Hotspur FC and Chelsea FC in their pursuit of any perpetrators and call for appropriate action to be taken by the authorities and the clubs.
"We appreciate the millions of supporters who help create a positive Premier League matchday atmosphere and have made it clear that racist conduct or language is unacceptable.
"The Premier League uses a protocol specifically designed to support players, managers and match officials who believe they are being subjected to discriminatory abuse during a match.
"This protocol is intended to ensure that abuse is stopped and offenders dealt with efficiently by clubs and police."