Passengers who witness people watching porn on public transport have been told to call the police.
Guidance issued by police also confirmed that people caught watching porn can be prosecuted for causing harassment, alarm or distress.
It follows a spate of such reports, with BBC Radio 4 raising the issue in Woman’s Hour on Monday after one of its reporters noticed a man watching porn on the bus during her commute.
Transport for London has previously urged passengers to report such incidents to a member of staff.
A British Transport Police spokesman said: “We are aware there has been some discussion in the media recently about people watching pornography on public transport and whether transport groups or the police can do anything about this.
“If you feel uncomfortable or distressed by someone who is looking at pornography on the railway, we want you to report it to us.
"There is various legislation which could potentially be used to prosecute this behaviour in some circumstances, including railway byelaws or Section 5 of the the Public Order Act for causing harassment, alarm or distress.
“You can use our discreet texting service - the number is 61016 - to report what is happening without those nearby overhearing, if this makes you feel more comfortable.”
