Southeastern rail passengers are facing higher fares on off peak journeys from the end of the month.
The rail operator is implementing increases of 3.4% or 10p, whichever is the greatest from May 21 2017. It passengers have not been informed of the increase however the company said it did not “routinely announce fare rises”
Campaigners described the move as “an appallingly high-handed way to treat passengers”.
About 640,000 journeys are currently made on 1,900 Southeastern trains every weekday.
Lianna Etkind of the Campaign for Better Transport said: “It’s bad enough that Southeastern passengers have had to put up with years of government-imposed peak fare rises while wages stagnate, but more back-door fare increase are unacceptable.
“We’re urging passengers to respond to the current Southeastern franchise consultation and tell the government that enough is enough, and passengers deserve proper value for money on their journeys.”
The rail company’s contract fro the running of the service expires in December next year.
Passengers in South-East London, Kent and East Sussex are being asked to give their views on the next franchise blue-print.
One option in the Department for Transport Consultation is a reduction in the number of trains calling at less well-used stations.
Under the proposals first-class travel could also be withdrawn.
The Department for Transport Consultation closes on 23 May 2017.