More than half of Wales' rail stations are not fully accessible to disabled people, according to a report.
The Welsh assembly equality of opportunity committee issued the findings, highlighting "significant shortcomings", and calling for action.
Arriva Trains Wales, which runs most of Wales' stations, said it was committed to improving access.
Joseph Carter, policy manager for the MS Society in Wales, said disabled people faced a "second class system".
He said: "Most disabled passengers as with any passengers want freedom to get on the train and go wherever they want rather than at the moment where theoretically there could be assistance if they ring ahead but where's the spontaneity there.
"You're creating a second class system where people who happen to be disabled can't have the same freedoms the rest of us enjoy."
Disabled people from across Wales gave written evidence to the committee, sharing their experiences.
The report from the cross-party group found issues including footbridge-only access to platforms, unreliable lifts, large gaps between trains and platforms and understaffing resulting in more than half of stations not being fully accessible.
It claims only 16% of stations have part access to the platforms for wheelchair users, and 34% no access.
The committee received examples of the difficulties encountered by disabled rail passengers.
Members of the Mid and West Wales ME Group said Machynlleth station posed a particular problem due to the large number of steps there to change platforms.
The committee heard of similar problems at Wrexham, Hawarden, Port Talbot, Neath and Chepstow.
"The current level of accessibility to railway stations in Wales is unacceptable and while we welcome the improvements that have taken place, we feel that much more could, and should, be done," said committee chair, Ann Jones, Clwyd West AM.
The report acknowledges that the assembly government does not have full control over the rail infrastructure in Wales, due to it being owned by Network Rail, operated by Arriva Trains Wales and controlled by the UK Government's Department for Transport.
However, it calls on ministers to use the powers under the Railways Act 2005 to finance further improvement initiatives and to influence the UK Government when it sets the next round of targets for Network Rail.
Kevin Fitzpatrick, a former disability rights commissioner for Wales, said he was not surprised by the report's findings.
He said: "No toilets on the train, very few toilets facilities in stations, very often not an opportunity to get some help or support at the station, no access to the station so for a very long time this has been a big issue and it's no that wonder disabled people don't travel by train.
"Would you take the chance of getting on a train at one point at a station that was accessible to arrive at another without knowing whether it was accesible or that support would be there?"
A spokesman for Arriva Trains Wales said: "When planning improvements to premises and trains, Arriva Trains Wales takes the needs and aspirations of customers with disabilities into consideration and is currently in the process of improving a number of stations around the UK in order to enhance the passenger journey experience.
"Improving accessibility is not an easy task as many of the UK's stations were built in the Victorian era and were not designed to meet the needs of passengers with reduced mobility.
The spokesman added they has made significant capital investment in improvements to stations and rolling stock against a limited franchise commitment and worked with other bodies to deliver the best possible service under its current agreement.
A Network Rail spokesperson said: "We are currently working with the industry to invest around £85m to improve stations in Wales by 2014, and part of that includes funding from Department for Transport to improve disabled access.
"Stations in Prestatyn, Wrexham, Bridgend and Severn Tunnel Junction are among those set to benefit. We share the aspiration to make even more railway stations accessible and we welcome further support from the government to help us achieve that."
Disabled rail passengers can get help planning their journey via the Journey Care Helpline on 0845 300 3005.