The introduction of so-called "smart" credit cards ran into difficulty yesterday in Britain as retailers threatened a boycott unless their concerns about how much it will cost them to adopt are met. British banks said they are now ready to adopt cards with microchips inside, which can carry much more information than traditional magnetic strip cards.

Chief among concerns are the cost of changing check-out systems and the fees that the banks will charge for handling transactions done on smart cards, a spokeswoman for the British Retailing Consortium said.