They were confirming a report in the Financial Times. "It's true," a diplomat close to the International Atomic Energy Agency (IAEA) said about the report.

But the diplomats said the discovery was not a "smoking gun" that could be used to take Iran before the UN Security Council, where it could face sanctions.

"It doesn't represent something new in terms of their capabilities," one diplomat said.

He said that if the IAEA found designs for actual weapons, "that would be the smoking gun, that's the killer" since Iran has repeatedly said its nuclear program is strictly for peaceful purposes.

The IAEA's board of governors is to meet March 8 to review the situation in Iran, following an ultimatum that expired last October 31 for the Islamic Republic to reveal all details of its nuclear program.

The IAEA said in November that Iran had been hiding sensitive details, including the enriching of uranium and plutonium, for 18 years.

Centrifuges are used to enrich uranium both for nuclear reactors and for atomic bombs.

Diplomats said the IAEA had used revelations made in dismantling Libya's atomic program to guide them to what the Iranians had.

"It's the same stuff that the Libyans had. It's really tracking along very much the same lines," a diplomat said.

Diplomats explained that the IAEA was guided by what they found in Libya to trace purchases made through the international black market in nuclear technology and then confront the Iranians with the evidence.

"You can follow a lot of information from a lot of different sources and finally present something to them that they can't deny," a Western diplomat said.

The father of Pakistan's atomic bomb, Abdul Qadeer Khan, has confessed to assembling a vast international network that helped both Libya and Iran to obtain centrifuge designs.

Nuclear experts in Vienna said Khan was selling designs for a basic centrifuge known as a G-1, which the Iranians had admitted to having, but that the new design was for a G-2, an improved and more efficient version.

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