They were confirming a report in The New York Times that the International Atomic Energy Agency (IAEA) has discovered that a giant cask of uranium hexafluoride (U6), which is raw material for centrifuges to enrich, had apparently come to Libya from North Korea in early 2001.

Citing unnamed US officials and European diplomats familiar with the intelligence, the Times said that the transaction, if confirmed, would be the first known case in which the North Korean government has sold a key ingredient for manufacturing atomic weapons to another country.

A senior Western diplomat, who asked not to be named, said the Vienna-based IAEA was in the middle of its investigation into this connection but "had not found explicitly the source" of the shipment.

The IAEA is "investigating where this U6 came from," said the diplomat, who asked not to be named.

Another senior Western diplomat described the Times report as "accurate."

He said the IAEA was basing its conclusion on interviews of members of the nuclear black market supply network set up by Abdul Qadeer Khan, the former head of Pakistan's main nuclear laboratory.

In a major revelation, Khan has admitted to selling nuclear technology to North Korea, Libya and Iran. The IAEA is trying to trace how Khan's network functioned.

IAEA spokesman Mark Gwozdecky said: "Our investigation into the black market continues. The IAEA continues to conduct interiews and work with many governments on three continents."

The IAEA is aiming to complete a report this week on Libya, ahead of a meeting of the agency's 35-nation board of governors on June 14 in Vienna, Gwozdecky said.

The uranium hexafluoride was turned over to the United States by the Libyans earlier this year as part of Libya's agreement to give up its nuclear program, and the Americans had first identified Pakistan as the likely source, according to The Times.

The uranium shipped to Libya could not be used as nuclear fuel unless it was enriched in centrifuges, which the Libyans were constructing as part of a 100-million-dollar program to purchase equipment from the Khan network, The Times said.

If enriched, the fuel obtained by Libya could produce a single nuclear weapon, the paper said, citing unnamed experts.

But the Libyan discovery suggests that North Korea may be capable of producing far larger quantities, especially because the country maintains huge uranium mines, The Times pointed out.

"The North Koreans have been selling missiles for years to many countries," the paper quoted one senior US administration official as saying. "Now, we have to look at their trading network in a very different context, to see if something much worse was happening as well."

Speaking in Crawford, Texas, White House spokesman Trent Duffy did not comment on the specifics of the Times report.

But he said it validated "the United States policy for North Korea to disarm in a complete, verifiable and irreversible fashion."

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