Auckland train passengers will begin using electronic swipe cards when the next phase of a new city-wide transport ticketing system is launched on Saturday.

The AT HOP cards will later be used on all public transport services - trains, buses and ferry journeys.

Across Auckland's rail network 145 card readers, 60 ticket and top-up machines and 29 entry and exit gates have been installed.

The new technology is similar to that seen in about 40 cities around the world, including the London Underground Oyster card system.

Passengers load money onto the card and swipe it on a card reader at the start and end of the journey. Passengers are charged a penalty fare if they don't swipe their card at the end of the journey.

AT HOP cards can be registered online which means a passenger will retain their balance if they lose the card.

Funds can also be added to a card, which are available for half price ($5) for a limited time, online.

Passengers can no longer buy tickets onboard trains.

Commuters will be able to use AT HOP cards on ferries next month and on buses next year.

Mayor Len Brown says he looks forward to the day when Aucklanders can use one card to take a bus, catch a ferry or board a train.

"Having one card that Aucklanders can use across the transport system will be a huge bonus for Aucklanders."

For a few months NZ Bus users who also use trains will have to use both the HOP/Snapper cards (which are used on NZ Bus services) and the AT HOP card.

The HOP/Snapper card will be phased out next year.

The Snapper system was cast aside from Auckland's integrated ticketing project after its owners couldn't make it compliant with the AT HOP system.