A group of Dutch scientists created a fake Oyster contactless travel card and used it to travel for free on London's underground transit system, according to local news reports. Researchers from Radbound University say they used a laptop to reverse the code in a contactless chip made by Netherlands-based NXP Semiconductors. The scientists first produced a fake building-access card to enter a Dutch building and then cloned an Oyster card for use on the London underground. The researchers say they discovered a major security flaw in the chip and alerted the Dutch government in March because "national security issues might be at stake." London transit officials say they run daily tests for cloned and fake cards and would stop any fake card discovered within 24 hours of detection. The Dutch government has delayed plans for a transit payment system similar to the Oyster card until the flaw is addressed.