Ministers are under pressure to cap rail fares amid union claims that they have risen twice as fast as incomes and predictions that they could rise by nearly 4% next year.
On Tuesday the percentage by which regulated rail fares will rise from January will be announced.
The Campaign for Better Transport (CfBT) said that although the 2015 Conservative manifesto pledged not to increase fares above inflation, July's RPI inflation figure is expected to be around 3.9% meaning that next year’s increase will be the highest since 2013.
It called for a fares freeze to hold regulated fares at their current level. It said: ‘The Government has frozen fuel duty for the last seven years and we think rail passengers should be given the same treatment.’
The campaign group also criticised ministers for continuing to use RPI to calculate annual fare increases, rather than the Consumer Price Index (CPI). It said RPI consistently overestimates real inflation and the Government has already switched to CPI for most other things.
The RMT union said fares have increased at twice the speed of wages since 2010. It said its analysis shows that fares have risen by around 32% in eight years, while average weekly earnings have only grown by 16%.
General secretary Mick Cash said: ‘The private operators and Government say the rises are necessary to fund investment but the reality is that they are pocketing the profits while passengers are paying more for less with rail engineering work being delayed or cancelled, skilled railway jobs being lost and staff cut on trains, stations and at ticket offices.’
Andy McDonald, Labour’s shadow transport secretary said: ‘It is outrageous that UK commuters pay over the odds in order to subsidise travel in France, Germany, Holland and Italy and generate huge profits for private train companies and foreign state-owned companies who run our railways.'
Mr McDonald also called for the RPI to be replaced with the CPI as the measure for increases.
The Rail Delivery Group, which represents train companies, said it was ‘politicians’ who set increases to season tickets. It said 97p in every pound from train fares goes back into running and improving the railway, while the other 3p 'enables investment by train companies'.
RDG added that passengers are now paying more of the cost of the railway – 71% compared to 57% in 2010-11 – while over the long-term, wages have grown faster than the price of train travel.
A spokesperson for the Department for Transport said: 'The Government carefully monitors how rail fares and average earnings change, and keeps under review the way fare levels are calculated.
‘We are investing in the biggest rail modernisation programme for over a century to improve services for passengers – providing faster and better trains with more seats. We have always fairly balanced the cost of this investment between the taxpayer and the passenger.’