Chelsea will support criminal prosecutions and ban any fans who were found to have prevented a black man from boarding a train in Paris and chanted: "We're racist and that's the way we like it."
Footage posted on The Guardian's website shows the commuter trying to board a Metro train in the French capital but he is blocked by what appears to be a group of Chelsea fans travelling to the Parc des Princes for the 1-1 draw with Paris St Germain on Tuesday night.
It has not been confirmed if the men on the train were Chelsea supporters heading to the Champions League clash, but the club released a statement condemning the incident and said they will take action if supporters are found to be involved.
"Such behaviour is abhorrent and has no place in football or society," a club spokesman 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."
Some individuals have been implicated on social media since the video was posted.
Chelsea are working with the relevant authorities to identify if those involved have season tickets or any other connection to the club.
The Metropolitan Police, which monitors supporters during European matches, is aware of the incident, and working with the French authorities.
Kick It Out chairman Lord Ouseley condemned the incident and called for Chelsea, and football, to avoid complacency over incidents of a similar nature.
Lord Ouseley told Press Association Sport: "We know that prejudice is on the increase and that in itself leads to hateful attitudes and this sort of conduct.
"I was shocked that Chelsea fans were still behaving like this. I thought the club had made it quite clear and taken action about stopping any repetition, knowing Chelsea, how hard they've worked on these matters, with fans as well as players, that it was unlikely to occur.
"The fact it involved an assault as well, of the individual that they pushed off the train, was even more shocking.
"Clearly it sends out a strong signal to, not only Chelsea, but the whole of football, that you cannot be complacent and think the actions you're taking are sufficient to deal with the scourge of racism, sexism, homophobia and anti-Semitism. We've got to do a lot more and not be complacent."
The Guardian reported that Paul Nolan, a British expatriate, filmed the clip on his phone on his way home from work.
"The doors were open and I could see and hear that a lot of chanting was going on," he told the newspaper. "It looked like it was quite aggressive so I just took out by phone to record it."
He added: "He (the commuter) 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.
"I was just completely appalled by it and so that's why I tried to catch some of it on my phone, although I was a bit self-conscious as it was getting quite aggressive and I overheard one of the Chelsea fans say something about stabbing someone. I think he was referring to a Paris St Germain supporter who was on the platform."
Kick It Out hopes anyone implicated is banned from football, not just Chelsea matches.
"We'll support any prosecution," Lord Ouseley added. "Chelsea need to make it quite clear, once again, that people who carry their prejudices around, please don't come to football.
"We need to see that reinforced by all clubs, because it's happening right across the country, not just one team.
"These attitudes are attitudes that are in our society and football can play a major part in helping to draw attention to ways in which we need to help people to change their attitudes."
Chelsea fanzine editor David Johnstone believes the incident could have severe consequences for the club's reputation.
"Because of the actions of possibly half a dozen people on a Metro train in Paris all the supporters are going to be labelled as racist," he told BBC Radio Five Live.
"I think the majority of Chelsea supporters are disgusted by what's happened. The 2,000 who were in Paris today support a Jewish-owned football team where the majority of players are black and foreign."
In the video the group of men are seen gesturing at the commuter and pushing him out of the carriage when he tries to step in.