Commuters face an average season ticket train fare hike of 3.5 per cent in January amid anger over high prices.

A retail price inflation figure of 2.5 per cent for July, which was announced today, will be used to calculate rail fares next year.

Under the formula, fares are due to increase by this measure of inflation, plus 1 per cent. But train companies also have a "flex" rule which allows them to increase some fares by an extra 2 per cent.

The increase on specific fares have yet to be announced, but if the cost of a Southern monthly season ticket between Epsom and London terminals does go up by 3.5 per cent - inflation plus one per cent - that would take the price from £180.10 to £186.40.

Martin Abrams, from the Campaign for Better Transport said: "By deliberately ramping up rail fares, Government is hitting the living standards of everyone who relies on the train to get to work.

"There are the large numbers of rail commuters living in marginal constituencies. They will be looking to Government to bring a permanent end to this annual fiasco."

This year ministers capped fare rises to keep them level with inflation but no such plan has yet been announced for 2015.

Rail minister Claire Perry said: "We do understand people’s concerns about the cost of travel and the impact this has on family budgets.

"That is why for 2014 we reduced average fare rises to RPI [Retail Price Index] plus 0 per cent for the first time in a decade, saving more than a quarter of a million annual season ticket holders an average of £25 each.

"Although a decision on fare rises for 2015 hasn’t yet been taken, we are looking closely at the cost of travel as part of our ongoing commitment to help hard-working people."

Michael Roberts, director general of the Rail Delivery Group (RDG), said rail fares pay for "more trains, better stations and faster services".

Mr Roberts said: "Government decides the average change to regulated fares, including season tickets, each year.

"For a decade, successive governments have regulated commuter fares so as to increase the share of rail’s costs paid by passengers rather than taxpayers."

A Southern spokeswoman said: "Regulated fares such as season tickets are set by Government, these are regulated so as to increase the share of rail’s costs paid by passengers rather than taxpayers.

"Money raised by regulated fares goes towards better trains, stations and services."

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