Police have released a CCTV image of a man they would like to speak to in relation to an incident of indecent exposure near Market Harborough.
The incident took place on board a train between London St Pancras and Nottingham.
British Transport Police said: “A man inappropriately touched himself whilst travelling on the service on Monday, September 7, at around 12.45pm. He left the service at Market Harborough.”
Investigating officer PC James Turnbull, said: “We simply will not tolerate behaviour such as this and we are working hard to find the person responsible.
“We take all reports of this nature very seriously and our recent Report It to Stop It campaign, which aims to combat unwanted sexual behaviour on the railway by encouraging members of the public to report it, is proving very successful in supporting victims and bringing perpetrators of these crimes to justice.”
Anyone with any information is asked to contact BTP by sending a text to 61016 or by calling 0800 40 50 40 quoting reference 175 of 12/9. Alternatively, information can be passed anonymously to independent charity Crimestoppers on 0800 555 111.