Thousands of commuters got a free ride into work this morning when London’s underground Oyster card system was plunged into chaos for the second time this month.

A problem with the flagship pay-as-you go system – which is yet to be fully fixed - kept barriers open throughout the busiest period of the morning, costing Transport For London (TFL) tens of thousands of pounds in lost fares.

Passengers touch the card on to an electronic reader when entering and leaving stations and money is deducted automatically from their account balance.

A station supervisor at Bank underground station, who did not wish to be named, told Times Online: “The system hasn’t been working since 5.30am, I don’t know how long it will take to resolve – how long is a piece of string?”

He said: “People haven’t been inconvenienced too much - in effect, Pay As You Go customers are getting a free ride. I’m sure they’re going to lose money but whoever is in charge of the IT system is going to have to foot the bill.”

One Tube worker at Tooting Broadway station said: “It’s Christmas come early for Pay As You Go customers.”

Today’s incident follows problems with Oyster two weeks ago when a fault left 40,000 customers with corrupted cards.

A Transport for London spokesperson said the problem was caused by an error on the part of Transys, the contractor in charge of the system, but Oyster card readers on London Buses, Trams and the Dockland’s Light Railway had not been affected. He said: "The problem has now been resolved and readers are progressively coming back on-line at stations.

"Cards have not being disabled as a result of the problem and we will automatically refund any passengers who may be charged the maximum £4 fare as a result of not being able to touch in and out at the beginning and end of their journeys. Oyster card holders need take no further action.

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