British police launched an investigation into further suspected racism involving Chelsea fans as the London club used Saturday's Premier League game to celebrate diversity in football.

Stickers emblazoned with "Support Chelsea Support Equality" were handed out at Stamford Bridge after a week when public acts of racism by some Chelsea fans brought a renewed focus on football's fight against discrimination.

Before Tuesday's Champions League game at Paris Saint-Germain, a black man was filmed being blocked from boarding a metro train by Chelsea fans, who then chanted: "We're racist and that's the way we like it."

Now British Transport Police has launched an appeal for witnesses, saying men "believed to be Chelsea supporters returning from Paris by train, shouted racist chants" at London's St. Pancras station on Wednesday night.

"It's clear that unfortunately there is still a minority who think it is acceptable to behave in such an abhorrent manner," police superintendent Gill Murray said after the incident was reported by a member of the public. "There is more that needs to be done to address the issue once and for all."

By coincidence, Chelsea had already designated Saturday's fixture against Burnley as its annual "Game for Equality" — when five people started provisional club bans from the west London stadium following the Paris incident, which drew widespread condemnation including from FIFA President Sepp Blatter and British Prime Minister David Cameron.

Chelsea's matchday program denounced the abuse over several pages, including a column by captain John Terry, who served a four-match Football Association ban in 2012 after being found guilty of racially abusing then-Queens Park Rangers player Anton Ferdinand in a game.

"This club stands against all forms of discrimination," Terry wrote. "Football is a sport for everyone, that is one of the main reasons why we love it."

Chelsea has issued a public apology to the man targeted by fans in Paris who was identified in French media as Souleymane S. The victim, whose last name has not been revealed, has been invited to London to watch the return leg against PSG next month. The first leg was a 1-1 draw.

The French presidential palace Twitter account said Saturday that President Francois Hollande has had a "discussion with Souleymane S. and gave him his full support following the odious racist aggression he suffered."

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AP Sports Writers Steve Douglas in London and Samuel Petrequin in Paris contributed to this report.