Police and train bosses are cracking down on begging on First Capital Connect trains after reports of people asking passengers for money.
Begging has become "somewhat of a problem" on services in and around the city, including services to and from St Albans, according to FCC.
There have also been reports of people moving through carriages leaving packets of tissues on seats with notes saying money is needed for children, rent, food or other necessities. People are asked to give money for the tissues and any not sold are collected.
Roger Perkins for First Capital Connect said:"Tissue begging has become something of a problem on services in and around the capital with various rail operators and it is something that can make our passengers feel particularly uncomfortable.
"That's why we would implore people to report any sightings to the British Transport Police who we work with closely to maintain security on the railways."
A British Transport Police spokesperson said some people involved in begging are "destitute".
He continued: "They are in need of help and we will try to direct them towards the appropriate services rather than criminalise them.
"It can be regarded as a problem in some areas and cover a wide spectrum of activity. Begging on trains or the Tube can be particularly intimidating for passengers and we will take appropriate action against those who are more aggressive and disruptive. In these cases they may be dealt with under Railway Byelaws or other legislation.
"Begging and similar anti-social activity can have a very negative effect on people’s perceptions of the station environment and increase their anxiety and fear of crime.
Anyone who witnesses criminality or anti-social behaviour on the rail network is asked to contact BTP on Freefone 0800 40 50 40 or text 61016.