Washington, June 15 : Electronic blueprints for an advanced nuclear weapon were found American and international investigators on computers that belonged to disgraced Pakistan nuclear scientist Abdul Qadeer Khan.
The New York Times reported that investigators were not able to determine whether the rogue Pakistani nuclear scientist sold those blueprints 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. But when confronted with the design by officials of the International Atomic Energy Agency last year, Pakistani officials insisted that Khan did not have access to Pakistan's weapons designs.
In interviews in Vienna, Islamabad and Washington over the past year, officials have said that the weapons design was far more sophisticated than the blueprints discovered in Libya in 2003.
Those blueprints were for a Chinese nuclear weapon that dated to the mid-1960s, and investigators found that Libya had obtained them from the Khan network, the NYT reported.
But the latest design found on Khan network computers in Switzerland, Bangkok and several other cities around the world is half the size and twice the power of the Chinese weapon, with far more modern electronics, the investigators said.
The design is in electronic form, they said, making it easy to copy and they have no idea how many copies of it are now in circulation.
Investigators said the evidence that the Khan network was trafficking in a tested, compact and efficient bomb design was particularly alarming, because if a country or group obtained the bomb design, the technological information would significantly shorten the time needed to build a weapon.
Among the missiles that could carry the smaller weapon, according to some weapons experts, is the Iranian Shahab III, which is based on a North Korean design.
However, in recent days top American intelligence officials, who declined to speak about the discovery on the record because the information is classified, said that they had been unable to determine whether Iran or other countries had obtained the weapons design.
Pakistan has refused to allow American investigators to directly interview Dr. Khan, who is considered a hero there as the father of its nuclear program.
In recent weeks the only communications about him between the United States and Pakistan's new government have been warnings from Washington not to allow him to be released.
Dr. Khan's illicit nuclear network was broken up in early 2004; President Bush declared that shattering the operation was a major intelligence coup for the United States.
Since then, evidence has emerged that the network sold uranium enrichment technology to Iran, North Korea and Libya, and investigators are still pursing leads that he may have done business with other countries as well.