Washington: An international smuggling ring once led by Pakistani scientist Abdul Qadeer Khan may have secretly shared blueprints for an advanced nuclear weapon with Iran, North Korea and other 'rogue' countries, according to a US daily.

The now-defunct ring, previously known to have sold bomb-related parts to Libya, Iran and North Korea, also acquired designs for building a more sophisticated compact nuclear device that could be fitted on a type of ballistic missile used by Iran and other developing countries, the Washington Post reported on Sunday.

Citing a draft report by former top UN arms inspector David Albright, the Post said the drawings were discovered in 2006 on computers owned by Swiss businessmen.

They were recently destroyed by the Swiss government under the supervision of the UN nuclear watchdog agency to keep them out of terrorists' hands. But UN officials said they couldn't rule out that the material already had been shared, the Post reported.

"These advanced nuclear weapons designs may have long ago been sold off to some of the most treacherous regimes in the world," Albright wrote in the draft report, which was expected to be published later this week, the daily said.

The New York Times too on Sunday cited American and international investigators as saying that they have found the electronic blueprints for an advanced nuclear weapon on computers that belonged to the A Q Khan network, but that they have not been able to determine whether they were sold to Iran or the smuggling ring's other customers.

The plans appear to closely resemble a nuclear weapon that was built by Pakistan and first tested exactly a decade ago, it said. A spokesman for the Pakistani Embassy in Washington, Nadeem Kiani, did not rebut the report's findings.

"The government of Pakistan has adequately investigated allegations of nuclear proliferation by A Q Khan and shared the information with" the UN's International Atomic Energy Agency (IAEA), Kiani told the Post.

"It considers the A Q Khan affair to be over." The Swiss government acknowledged this month that it destroyed nuclear-related documents, including weapons-design details, under the direction of the UN's International Atomic Energy Agency (IAEA) to keep them from falling into terrorists' hands.

However, it has not been previously reported that the documents included hundreds of pages of specifications for a second, more advanced nuclear bomb, the Post said.

"These would have been ideal for two of Khan's other major customers, Iran and North Korea," wrote Albright, now president of the Washington-based Institute for Science and International Security. "They both faced struggles in building a nuclear warhead small enough to fit atop their ballistic missiles, and these designs were for a warhead that would fit."

It is unknown whether the designs were delivered to either country, or to anyone else, Albright said. A CIA official, informed of the essential details of Albright's report, said the agency would not comment because of the extreme diplomatic and security sensitivities of the matter. In his 2007 memoir, former CIA director George Tenet acknowledged the agency's extensive involvement in tracking the Khan network over more than a decade.

Albright, a former IAEA inspector in Iraq, citing information provided by IAEA investigators, said the designs were similar to that of a nuclear device built by Pakistan. Pakistan has previously denied that Khan stole the country's weapons plans.

Albright said it remains critical that investigators press Khan and others for details about how the blueprints were obtained and who might have them. Because the plans were stored electronically, they may have been copied many times, he said.

Source : IANS