London's underground Oyster card system failed again during the morning rush-hour today.
A problem with the system - the second this month - meant that ticket barriers at Tube stations had to be kept open at all stations.
All pay-as-you-go Oyster cards were affected. These can be used on the Tube, buses, trams and the Docklands Light Railway in London although today's problem only affected the Underground.
Passengers touch the card on to an electronic reader when entering and leaving stations.
Transport for London (TfL) said the barriers at stations were being kept open to minimise disruption at Tube stations while engineers worked to resolve the problem.
A TfL spokesman added that Oyster card holders affected would not be out of pocket as a result of today's problem and did not need to take any action.
Today's incident follows problems with Oyster two weeks ago when a fault left 40,000 customers with corrupted cards.Reuse content