ISLAMABAD, Pakistan — Rogue Pakistani nuclear scientist A.Q. Khan on Tuesday angrily rejected chilling new allegations against him that he sold a blueprint for a sophisticated nuclear warhead, claiming that Pakistan did not have the technology to have produced the design.
Khan suggested that those newly discovered designs could only have come from the United States, Russia, or possibly France or Great Britain.
In a telephone interview with McClatchy on Tuesday, Khan denied that he was the culprit, calling the allegations: "All bullshit, all pure bullshit." Khan, who remains under house arrest at his villa here, added: "Even when I'm gone, there will be allegations"
The new charges were made in a report this week from an independent Washington-based research group, the Institute for Science and International Security, which revealed that Swiss authorities had found a design for a miniaturized nuclear warhead on the computer of Khan's business partners in Switzerland.
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The report said Khan stole the design from the Pakistani nuclear program and passed it to his business associates, the Tinner family, to sell. Previously, Khan had been accused of proliferating nuclear enrichment technology, not warhead designs.
In the interview, Khan admitted dealing with the Tinner family, but as a customer. He denied supplying them with the warhead plan.
"They've (the Tinners) been supplying to Pakistan, India, Iran. This has been a business for 30 years, 40 years. They were suppliers to us, they were suppliers to any country that was involved in high tech," said Khan.
The issue could be vital for nuclear proliferation. The blueprint was for a warhead small enough to mount on a missile, knowledge that would knock years off the time required for a country like Iran to effectively create a tactical atomic weapon.
Iran was a major customer of the A.Q. Khan network, but it is not known who bought a copy of the warhead design from the smuggling ring.
Khan claimed that Pakistan had not developed the technology required for a small warhead, so he could not have passed it on.
"(The design) must have come from the Americans," he told McClatchy. "We don't have the small warheads. Only the Americans have, the Russians have. It must have come from there. ... And the French maybe, and the British maybe."
Asked if Pakistan had the means to produce the blueprint, he said, "No".
"I don't think so, at least not when I was there. We were not working on it," Khan added.
David Albright, a former U.N. weapons inspector who wrote the report, said that the Bush administration had failed to press Pakistani authorities to get information from Khan over who could have the design. It could even have fallen into the hands of terrorists, Albright said.
"We want to know when Iran could have a nuclear arsenal," said Albright. "We do want to know how quickly they could weaponize ... I'm releasing this to put pressure on the U.S. government."
Khan headed Pakistan's clandestine nuclear program from the mid-1970s until he was removed from the job in 2004, after the United States confronted Islamabad with evidence of his proliferation activities. He confessed, at the time, to selling technology for enriching uranium, one of the methods for producing a nuclear bomb, to Iran, Libya and North Korea.
In an earlier interview with McClatchy, Khan retracted his confession.
The new charges against him add greatly to the menace that he is alleged to have posed to the world. "Khan sought to offer one-stop shopping for a nuclear arsenal," said the Institute for Science and International Security report.
Last year, the Swiss authorities announced they had destroyed weapons designs they discovered that were linked to Khan's network. But the nature of those designs — that they were for a compact warhead — was not known until the ISIS report. The Khan network previously had been accused of selling a warhead design to the Libyans, but that blueprint was too bulky to mount on a missile.
According to the report, information gleaned from Pakistani officials, together with Khan's known connection with the Tinners, meant that the compact design came from Islamabad's program. The ISIS report disclosed that officials from the U.N. nuclear watchdog, the International Atomic Energy Authority, quietly challenged the Pakistani government in 2006 over the discovery.
"The Pakistanis were upset, since they realized that the designs had to be from their nuclear weapons arsenal," the ISIS report said. "They were genuinely shocked; Khan may have transferred his own country's most secret and dangerous information to foreign smugglers so that they could sell it for a profit."
Albright said that the Pakistanis possessed the required technology and had mounted just such a compact warhead on the country's Ghauri missile.
"This makes Khan a traitor," said Albright. "It's been four years since his arrest and questions still need to be answered."
(Shah is a McClatchy special correspondent.)