WASHINGTON, Feb 15: The nuclear designs that Libya obtained from a Pakistani smuggling network originated in China, confirming US intelligence reports that China helped Pakistan build its first nuclear weapon, US media reported on Sunday.

The report claimed that the "dramatic evidence" of China's role in transferring nuclear know-how to Pakistan in the early 1980s was found in the papers Libya had surrendered to American and British investigators.

The report, first published by the Washington Post and later also broadcast by several television networks, said that a trading network allegedly led by Dr A. Q. Khan resold the Chinese designs to Libya.

The Libyan documents contained detailed, step-by-step instructions for assembling an implosion-type nuclear bomb that could fit atop a large ballistic missile. They also included technical instructions for manufacturing components for the device, the report said.

The documents, the report said, reveal "a wholesale transfer of nuclear technology" from China to Pakistan. The report claims that China continued to mentor Pakistani scientists on the finer points of bomb-building over a period of several years.

"These documents also raise questions about whether Iran, North Korea and perhaps others received these documents from Pakistanis or their agents," says David Albright, a nuclear physicist and former UN weapons inspector in Iraq.

Libya turned over the documents to US officials in November following Libyan leader Moammar Qadhafi's decision to renounce weapons of mass destruction and open his country's weapons laboratories to international inspection.

The blueprints, which were flown to Washington last month, have been analyzed by experts from the United States, Britain and the Vienna-based International Atomic Energy Agency, the report said.

Western weapons experts in Libya also found large amounts of equipment used in making enriched uranium, the essential ingredient in nuclear weapons. That discovery helped expose a rogue nuclear trading network that officials say funnelled technology and parts to Libya as well as Iran and North Korea, the report said.