WASHINGTON - An international smuggling ring managed to acquire blueprints for an advanced nuclear weapon, a former UN arms inspector is to say in a new report, according to The Washington Post. David Albright, who investigated the ring led by Pakistani scientist AQ Khan, found the drawings in 2006, the newspaper said. His report, due to be published later this week but seen in advance by The Post, suggests the plans may have been sold to rogue regimes. The blueprints included key details for building a compact nuclear device. Such a device, unlike less advanced ones, could be fitted to the kind of ballistic missile used by Iran and more than a dozen developing countries. A spokesman for the Pakistan Embassy, who was asked to comment on the report's finding by The Washington Post, said his government had cooperated extensively with UN investigators. "The government of Pakistan has adequately investigated allegations of nuclear proliferation by AQ Khan and shared the information with IAEA," Nadeem Kiani, was quoted as saying. "It considers the AQ Khan affair to be over." The computer contents - among more than 1,000 gigabytes of data seized - were recently destroyed by Swiss authorities under the supervision of the International Atomic Energy Agency. But UN officials cannot rule out the possibility that the blueprints were shared with others before their discovery, Albright, the report's author, told The Post. "These advanced nuclear weapons designs may have long ago been sold off to some of the most treacherous regimes in the world," the paper quotes Albright as saying in his report. The AQ Khan network was previously alleged to have provided Libya with design information for a nuclear bomb. But the blueprints found in 2006 are far more troubling, Albright said, because they offered instructions for building a compact device. The lethality of such a bomb would not be significantly enhanced, but its smaller size might allow for delivery by ballistic missile, the paper said.