Police are investigating whether any of the Chelsea fans who were filmed stopping a black man getting on a train in Paris can be banned from football.
The club has condemned the supporters' behaviour as "abhorrent" and says it will support any criminal action against them.
They are believed to have been travelling to the Parc des Princes stadium for a Champions League game against Paris Saint Germain, which ended in a 1-1 draw.
The Metropolitan Police said it was aware of the incident and was working with the French authorities.
The Parc des Princes stadium in Paris
It said: "We will examine the footage with a view to seeing if we can apply for football banning orders, preventing people from travelling from future matches."
Footage on The Guardian newspaper's website shows the commuter trying to board a metro train at Richelieu-Drouot station.
A group of supporters are seen shouting and gesturing at the man and chanting "Chelsea, Chelsea, Chelsea", before pushing him away as he tries to step into the carriage.
The man attempts to get on the train again, pointing to a space where he could stand, but is pushed back once more as he moves forward.
The fans then chant: "We're racist, we're racist, and that's the way we like it."
The supporters are also heard chanting: "Where were you in World War Two?"
British expatriate Paul Nolan, who filmed the incident, said: "He was obviously completely shocked when they pushed him off.
"I don't think he realised who they were. He then tried to get on again and got pushed off a second time."
Chelsea vowed to take "the strongest possible" action if members are found to have been involved and appealed for anyone with information to come forward.
A club statement said: "We will support any criminal action against those involved, and should evidence point to involvement of Chelsea season-ticket holders or members the club will take the strongest possible action against them, including banning orders."
on">Chelsea Fan: It Was Self-Defence
A Chelsea fan at the scene defended the actions of the group, insisting they were chanting about club captain John Terry and that other passengers were also prevented from boarding the train.
Mitchell McCoy, 17, said: "I'm not in the video but I'm on the carriage. We got on the train and at the station where the man was trying to get on we stopped for a couple of minutes.
"He tried to get on and a few people were pushing him off because there wasn't much space. You couldn't move.
"People were saying it was because he was black. It's not true at all."
Mr McCoy said the song was about Terry, who was banned for four matches by the Football Association for racially abusing QPR's Anton Ferdinand in 2011.
The regulatory commission which ruled on the case stated that the Chelsea captain was "not a racist".
Kick It Out chairman Lord Ouseley condemned the fans' behaviour and said the anti-discrimination body would support any prosecutions.
Prime Minister David Cameron told LBC Radio: "This does look extremely disturbing and very worrying. It's obviously potentially a criminal offence and so I'm sure the French police will be looking at it very seriously."