A Dutch court has ruled that details of how to copy the technology used in the Oyster card can be made public. NXP, the company that makes the London smart card, had sought an injunction in June after a Dutch research team showed how to duplicate the system's computer chip.

Researchers from Radboud University discovered security weaknesses in the Mifare Classic chip which is used in smart cards in London, Holland and Hong Kong. The research team at the Dutch university informed NXP of their findings to allow the company to take appropriate security measures.

There are over 17m Oyster cards in use in England and NXP told Reuters that it could take years for some companies that use the Mifare Classic to meet the new security needs. But security expert Bruce Schneier told the BBC that it would be naive to think that organised crime syndicates haven't already targeted the weaknesses in the smart card technology.