It bought centrifuge designs from Pakistan and imported technology from a secret network of suppliers that spanned the globe.

Dr. Khan was accused of stealing a centrifuge design from a European company in the early 1970's.

At around the same time, Iran made its secret deal and obtained basic centrifuge designs, the ones that now bear Pakistan's technological signature.

The company wants to incorporate advanced composite materials into the Energy Department's older centrifuge design.

American intelligence officials also believe that within the last two years Pakistani centrifuge designs helped Libya's nuclear program.

The centrifuge design is known as a "Pak-2," indicating that it was a second-generation version that probably dates from the late 1980's, American officials said.

His claim to fame was as a metallurgist who perfected the rotors on the centrifuge design that he stole from a Dutch plant.

And they cannot assure the truth of Iran's claims that after receiving more advanced centrifuge designs in 1995, it did nothing with them until 2002.

This improved centrifuge design is used by the commercial company Urenco to produce enriched uranium fuel for nuclear power stations.

In 2000, Khan provided sensitive centrifuge designs to Tinner on gas-centrifuge method.