Global Nuclear Inquiry Stalls

International authorities fear the full scope of the Pakistani scientist's ring may never be known.

Senior investigators said they were especially worried that dangerous elements of the illicit network of manufacturers and suppliers would remain undetected and capable of resuming operations once international pressures eased.

Investigators also said that records obtained in Libya and elsewhere showed that some nuclear equipment purchased or manufactured by the network had yet to be found, raising the possibility that it was diverted to still unidentified customers.

"We are far from knowing everything," a senior European diplomat involved in the inquiry said. "I'm frustrated by the lack of cooperation. We are losing a lot of time."

Some countries have refused to help, and others have only partially cooperated, said numerous officials involved in the inquiry spearheaded by the United Nations' International Atomic Energy Agency, or IAEA.

Pakistan has not permitted investigators to interview Khan, and his closest confidant is being held in Malaysia under that country's restrictive security act. Investigators also are concerned about the level of cooperation of former Soviet republics and China.

Investigators have suffered setbacks and delays even as they have gathered new evidence of the network's sophistication and have documented its move into Dubai, an ancient smuggling port on the Persian Gulf. Dubai was the hub of Khan's covert distribution operation, a transportation and storage base for parts and machinery destined for the secret nuclear programs in Iran and Libya, shipping records and investigation files show.

The Khan ring used nondescript warehouses scattered throughout Dubai, in the United Arab Emirates, to store and repackage some of the equipment, as well as to complete small-scale manufacturing assignments, according to documents and photos shown to The Times.

Inspectors from the IAEA visited the warehouses in recent weeks and took environmental samples to check for the presence of enriched uranium, which could indicate the shipment of weapons material. Test results are pending, officials said.