Police are investigating a second allegation of racism by Chelsea fans following the team's match against Paris Saint-Germain in midweek.
The club issued an apology yesterday after footage emerged of supporters stopping a black man from getting on the Paris Metro on Tuesday night.
Five men have been suspended from attending games at Stamford Bridge as a result of the incident.
British Transport Police are now looking into a fresh allegation of racist chanting by a group of men thought to be Chelsea fans at London's St Pancras station on Wednesday.
"It is clear that there is still a minority who think it is acceptable to behave in such an abhorrent manner," a police spokesman is quoted as saying by Sky Sports News. "The BTP are working actively with football clubs and the relevant authorities to tackle this appalling behaviour."
Chelsea are back in action this afternoon when they host Burnley in the Premier League.