Rail commuters are to face average fare hikes of eight per cent next year as official figures showed the retail prices index had remained unchanged in July at five per cent.

Train fares for the new year are in most places calculated by adding three per cent to the RPI rate of inflation for the month after the government changed the formula from adding just one per cent to the rate.

The rises will hit consumers who are already faced with rises in household rent and maintenance, energy bills and petrol at a time when few are receiving meaningful wage increases.

Alexandra Woodsworth from the Campaign for Better Transport's said the rises would "deal a fresh blow to commuters already facing the financial crunch of rising costs combined with frozen wages.

"We need affordable rail travel - not only to give passengers a fair deal, but to protect the economic health of our major cities, and to address the urgent imperative to cut carbon emissions."

Campaigners are staging a protest outside London's Waterloo station in an attempt to pressure the government to stop rail fare hikes.

Jonathan Edwards, Plaid Cymru's Transport spokesperson, said the coalition government was "cheating" the people of Wales with the price hike.

“Ticket price rises like this will push people away from the train and make it more difficult for some to afford to get into work," he said.

“The UK Government has changed the rules of the game in their favour, and against transport users."

Figures released by the Office for National Statistics on Tuesday also showed the consumer prices index had risen to 4.4 per cent in July, up from 4.2 per cent.

The increase is likely to add pressure to the Bank of England to push up interest rates.