NEW YORK, Feb 4: The United States has obtained from Libya a small box containing warhead designs that American officials believe were sold to Tripoli by the underground network linked to Dr Abdul Qadeer Khan , The New York Times said on Wednesday.

Experts familiar with the contents of the box say the designs closely resemble the warheads that China tested in the late 1960s and passed on to Pakistan decades ago, the Times said.

The paper said that according to American and European investigators, the network that supplied Libya was enormously complex, and not all the paths led directly back to the Khan Research Laboratories. Centrifuge parts were made in Malaysia, and other parts were obtained in Germany and Japan. The Japanese last year seized critical equipment headed for North Korea.

But both the centrifuge designs and the bomb designs seized in Libya appear to have come from the same country, according to experts. "My understanding is that it did come from Pakistan," David Albright, a physicist and President of the Institute for Science and International Security told the paper.

The evidence flown in a charted Boeing 747 had warhead designs which were the first hard evidence that the secret network provided its customers with far more than just the technology to turn uranium into bomb fuel, the paper said.