Police are examining mobile phone footage following reports of racist and abusive behavior by Chelsea fans on a train on Sunday night.
British Transport Police (BTP) said they were called to meet the London to Manchester train as it entered Stoke station, and asked four men to leave. Four others left of their own accord.
It follows an alleged racist incident involving Chelsea supporters on the Paris Metro last month ahead of the club's Champions League last 16 first leg clash with Paris St Germain.
That incident is still being investigated by British and French authorities, but five supporters were suspended by Chelsea and could be banned for life by the club.
A BTP spokesman said: "Shortly after 10.30pm on Sunday, March 1, officers were called to meet a Euston to Manchester Piccadilly train at Stoke, following reports of racist and abusive behavior by a number of passengers, said to be football fans.
"Colleagues from Staffordshire Police also attended. Officers asked four men to leave the train at Stoke. We have spoken to two witnesses, and investigations continue.
"Rail passengers and staff have the right to travel and work in peace. Abusive behavior on trains and at stations is unacceptable and we will not hesitate to investigate any such incidents."
The BTP spokesman said passengers claimed the abusive fans were Chelsea supporters, but this is being investigated.
BTP are examining mobile phone footage of the incident, which the force obtained from a witness.
No details have emerged of the abuse or racist language alleged to have been used.
A Chelsea spokesman told Press Association Sport: "We are aware of the reports but it is not clear at this time if this incident involves Chelsea supporters.
"If it did then we will assist the British Transport Police with their inquiries."
The latest incident occurred after Chelsea beat Tottenham 2-0 to win the Capital One Cup at Wembley on Sunday.
Chelsea reacted swiftly to the incident on the Paris Metro and can be expected to take similarly strong action should any of those involved in the latest incident be found to have a connection with the club.
Chelsea banned five fans following their own investigation into the Paris Metro incident, when a commuter, identified in media reports as French-Mauritian Souleymane S, was blocked from boarding a train by fans traveling to the Parc des Princes for the Champions League match on February 17.
Footage captured by a bystander appeared to show Souleymane being pushed back on to the platform amid chants of "we're racist, we're racist and that's the way we like it".
Another group of fans returning from Paris were heard shouting racist chants at London's St Pancras station.
Chelsea manager Jose Mourinho said he was "ashamed" by the events in Paris, while owner Roman Abramovich was said to be "disgusted".
The Blues were "appalled by what we saw", branding the incident as "unforgivable" and declaring that "the people involved do not represent Chelsea football club".
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