Updated Commuters are travelling for free on the London Underground this morning after technical problems again brought down the Oyster ticket system.

Gates have been left open since early this morning. But at least this failure is not knackering people's cards - the downtime last time meant 35,000 people had to get their cards replaced. Oyster readers on trams and buses are working normally.

Transport for London is stressing that this time no cards will need replacing. The MiFare chip, on which Oyster cards are based, were recently cracked and cloned by Dutch researchers.

A Transport for London spokesperson said:

There is currently a technical problem with Oyster readers at London Underground stations which is affecting Oyster pay as you go cards only. Ticket gatelines have been opened to minimise any disruption to passengers whilst we resolve the problem. Oyster card readers on London Buses and on the Tram network are unaffected.

Cards are 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.

We believe that this problem, like the last one resulted from incorrect data tables being sent out by our contractor, Transys.

TfL has denied this has anything to do with the two recent failures but it has been suggested that security updates to try and protect the system against cloned cards caused the problems.

Update

We received a further statement from Transport for London:

The problem has now been resolved and readers are progressively coming back on-line at stations.

So all's well that ends well. ®

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