Appeal after Stoke and Leicester fans clash on train
Police officers were assaulted and rail staff abused when disorder broke out following a football match between Stoke City and Leicester City.
The disorder happened on two trains from Leicester to Derby, British Transport Police (BTP) said.
It followed a Barclays Premier League match between the two teams, which Stoke won 1-0.
Det Insp Gareth Davies said a large number of fans had been on the 18:01 and 18:30 services on Saturday.
"We are investigating reports of a number of incidents taking place on both trains including police officers being assaulted, members of rail staff being abused and passengers, including other football fans, being intimidated."
He said the emergency cord was pulled on the earlier train, bringing it to a standstill and causing "significant delays" for passengers.
Mr Davies said officers were reviewing CCTV footage, but urged anyone who witnessed the disorder to come forward.