An international smuggling ring may have secretly shared blueprints for an advanced nuclear weapon with Iran, North Korea and other countries, the Washington Post reported on Sunday.

The now-defunct ring led by Pakistani scientist Abdul Qadeer Khan is previously known to have sold bomb-related parts to Libya, Iran and North Korea.

The Post, citing a draft report by former top UN arms inspector David Albright, says the smugglers 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 drawings were discovered in 2006 on computers owned by Swiss businessmen. The Swiss government recently destroyed the drawings under the supervision of the UN nuclear watchdog agency.

But UN officials said they couldn't rule out that the material already had been shared.

"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.
Allegations 'adequately investigated'

Nadeem Kiani, a spokesman for the Pakistani Embassy in Washington, did not rebut the report's findings, but he said the Khan affair is now considered to "be over."

"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]," Kiani told the Post.

U.S. security adviser Stephen Hadley said he hadn't yet read accounts of the Albright report.

"But obviously we're very concerned about the A.Q. Khan network, both in terms of what they were doing by purveying enrichment technology and also the possibility that there would be weapons-related technology associated with it," he said.

In Vienna, a senior diplomat said the IAEA knew of the existence of a sophisticated nuclear weapons design being peddled electronically by the black-market ring as far back as 2005.

The diplomat, who is familiar with the investigations into the A.Q. Khan network, spoke on condition of anonymity because he wasn't authorized to comment publicly on the issue.

The diplomat said IAEA chief Mohamed ElBaradei has publicly expressed concern about who potentially had come in possession of the information. The diplomat pointed to a transcript of a panel discussion on Nov. 7, 2005, where ElBaradei spoke of at least one weapons design being copied by the Khan network onto a CD-ROM "that went somewhere that we haven't seen."