Train operator c2c has become the first mainline train operator to accept the deal, allowing their passengers to get the benefits of Oyster pay as you go.

This follows the Mayor's announcement this week that the 10 millionth Oyster card has been issued.

Ken Livingstone said: "This is extremely good news and will bring real benefits to the commuters who use these services.

"I welcome c2c's decision to adopt Oyster at their stations allowing their passengers to get the full benefit of Oyster including pay as you go.

"c2c has shown that there is no justifiable reason why other train operating companies should not also accept my offer to pay them £20m to install Oyster equipment.

"This represents a unique opportunity for passengers to benefit from the convenience and cheaper travel available through Oyster, and a fully integrated ticketing system in London."

In May 2006, the Mayor offered a funding package of £20m to the train operators, which will finance the technology to accept the pay as you go system to be bought and installed at every station in Zones 1-6.

The train operating companies have until 31st January to accept this deal.

With the introduction on the rail system of the familiar six zones already used for Underground and Travelcard tickets, London can move to a unified ticketing system based on the Oyster smart card.

Integrated journeys

Transport for London (TfL) Commissioner Peter Hendy said: "This is great news for passengers as a further step toward to a fully integrated ticket system in London.

"This means even more passengers will be able to move easily between rail, Tube, DLR, tram and bus using an Oyster card."

Around three quarters of journeys on London's buses and Underground are now paid for by Oyster card compared to only five per cent by cash - bringing huge time savings to passengers and the transport system.

Almost three times as many passengers can pass an Underground payment gate using Oyster card as can using printed tickets - 40-a-minute compared to 15-a-minute.