The number of crimes at overground stations outside London's zone one rose by 2,000 last year, a report has said.
The London Assembly study showed that the number of reported crimes was 12,260 in 2002/03.
The worst affected stations were East Croydon, Clapham Junction and Walthamstow Central.
London Assembly member Roger Evans blamed a lack of joined-up thinking between railway companies and councils as well as a lack of station staff.
He said: "These incidents are a warning that urgent improvements are needed to safeguard passengers.
"It is unacceptable that many of London's train stations are unwelcoming and threatening areas, especially during evenings."
The assembly's transport committee, which will discuss the report later, said more British Transport police were needed as well as staff at stations at off-peak times.
It also called for stricter standards in train franchises for better passenger safety.
Figures show that 83% of crimes were against people aged under 40.