A 39-year-man was arrested after a woman was allegedly sexually assaulted on board a train to Cleethorpes.
The incident happened on board a TransPennine Manchester to Cleethorpes service at around 4.40pm on March 6. The train was travelling between Doncaster and Scunthorpe at the time.
A 39-year-old man was arrested and has been released under investigation while enquiries continue.
British Transport Police want to speak to anyone who witnessed the incident, in particular a group of women who spoke to the victim at the time that may be able to help with the investigation.
Anyone with information should contact British Transport Police by texting 61016 or by calling 0800 40 50 40 quoting reference 435 of March 6.
It can also be reported anonymously through Crimestoppers on 0800 555 111.