Southeastern to increase off-peak fares
Rail passengers on off-peak Southeastern services are facing higher fares from 21 May.
The rail operator is implementing increases of 3.4% or 10p, whichever is the greatest.
Southeastern has not informed passengers of the increase but 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 made on 1,900 Southeastern trains every weekday.
The firm said it kept fare increases to a minimum and had "frozen some fares for the past three years".
Advanced fares remain at January 2016 prices, it added.
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 increases 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."
Southeastern's contract to run the service expires in December 2018.
Passengers in south-east London, Kent and East Sussex are being asked to give their views on the next franchise blueprint.
One of the options being explored by the Department for Transport (DfT) consultation is a reduction in the number of trains that call at some less well-used stations.
Under the proposals first-class travel could also be withdrawn.
The DfT consultation closes on 23 May.