The Mayor of London wants the government to freeze fares across the capital's suburban rail services.
Sadiq Khan said that a potential rise of up to five per cent on some lines will be a "kick in the teeth" for long-suffering passengers.
Transport for London's pay as you go fares have been frozen for the next four years, but rail fares across the UK are expected to increase by 1.9 per cent in January (the RPI figure for July 2016). Train companies can also decide to increase fares by 10p each journey, as opposed to by RPI, which Khan says means some pay as you go fares could increase by as much as five per cent this January.
In 2015, all train operating firms in London chose to increase pay as you go fares in London by 10p, rather than RPI.
For far too long, Londoners using our suburban rail routes have been getting a terrible service - with delays, overcrowding and cancellations becoming the norm. Commuters will understandably be furious when they hear that fares on some routes face being hiked another five per cent this January. It's another kick in the teeth for long-suffering rail passengers.
Under fares regulation, government sets a broad framework for fares but each train operator is responsible for setting the specific fares on its routes. Within the capital, National Rail fares follow common zonal scales set by the London train operating firms collectively.
Under their agreements, each operator (or the collective group in the capital) may currently increase any individual regulated fare by no more than RPI or 10p, whichever is higher, each year.
Southern Rail passengers have suffered more than most this year as the franchise has been beset by strikes through a nine-month dispute with the Rail, Maritime and Transport union.
Last month, Khan presented transport secretary Chris Grayling with the business case for further devolution of London's suburban rail services to TfL. Southeastern London services could be transferred when the current franchise ends in 2018.