The UN's nuclear watchdog, the IAEA, has said questions remain about Libya's nuclear weapons programme, despite its promise last December to scrap it. In a confidential report, the IAEA said it was happy with Libya's co-operation but that investigations must continue. It said some of Libya's nuclear equipment had been contaminated with highly enriched uranium, which can be used to make nuclear weapons. But it said there was no evidence Libya had begun building a nuclear warhead. The leaked report linked Libya to an international black market in nuclear equipment run by the Pakistani scientist AQ Khan. The IAEA said it found the uranium on centrifuges which Libya bought on the black market network.