Some rail passengers will have to fork out for fare rises of up to 145 per cent from next week.
The East Midlands Trains company is making alterations to some of its Travelcard tickets which will affect passengers travelling in the morning from Market Harborough, Kettering and Wellingborough to London.
This will mean that from this Sunday there will be more expensive fares for those arriving in London after 9.45am and before 11.29am.
Other fares are coming down, with some long-distance commuters on East Midlands' lines getting reductions of up to 28 per cent.
Ashwin Kumar, director of rail customer watchdog Passenger Focus, said: "This is yet another example of a train operating company rolling out a back-door fare rise by tinkering with ticket restrictions.
"Passengers will be aghast that a train company can double the cost of these fares in one fell swoop. The industry and government must produce a fare system which is affordable and transparent if it is to keep passengers on the train."
On the BBC website, Steve Jones, chairman of Harborough Rail Users Group, said: "My immediate reaction is shock, there is no other word for it."
"For the people catching these trains, who have built their working lives around them, this is a massive increase."Reuse content