Oysters for all trains unless you take SWT

Passengers will be able to use their Oyster cards on almost all of London's rail network by the end of the summer, the Standard has learned.

Underground and overground services will be "fully integrated" for commuters travelling from railway stations in the outer boroughs.

Boris Johnson is expected to make an announcement next week that Oyster cards will be accepted on almost all suburban trains -including for pay-as-you-go trips - from September.

The only exception will be for passengers on South West Trains covering routes from Waterloo to locations including Kingston and Basingstoke. They will have to wait for the completion of franchise negotiations with the Department for Transport.

The Mayor has put pressure on the Association of Train Operating Companies to let Oyster cards be used on all services ever since he took over at City Hall.

The 10 train operators resisted because of the costs of maintaining the readers and sales equipment and fears that fare evasion would increase as not all stations have automatic ticket barriers.

Transport for London is now installing Oyster machines at all stations across the city at a cost to the taxpayer of £40 million.

At a transport safety event yesterday, Mr Johnson said it was "crazy that commuters still had to buy a paper ticket to travel into London" and added: "I look forward to the day when you can use the same Oyster card to get round the whole of the capital."

A senior TfL source said a decision was expected next week. He added: "The equipment is being installed at our expense in every train station in London that hasn't got it, apart from SWT. We're hopeful the Mayor will be able to say something next week."

Evening Standard understands commercial directors of the train companies are meeting today to discuss the roll-out, with the plan expected to be agreed at an ATOC board meeting next week.

The move will benefit passengers who want to use Oyster but do not have a weekly or monthly rail pass to put on their cards. It could also help those who qualify for cut-price travel with Oyster but not on mainline rail tickets, although train firms are still expected to set full-price and season ticket fares.

A TfL spokesman said it was optimistic that Oyster cards would "be accepted on all rail services in Greater London by the end of this year".

Passengers on SWT will not be able to use an Oyster card for pay as you go, although they can load their season ticket onto one.

SWT wants to apply its own, more expensive, fares structure, and has other demands to which TfL is unable to agree. As things stand, it would only accept Oyster pay-as-you-go if readers across the Tube, bus and rail network were compatible with planned ITSO transport smartcards.