Iran is poised to greatly expand uranium enrichment at a fortified underground bunker to a point that would boost how quickly it could make nuclear warheads, diplomats tell the Associated Press.
They said Tehran has put finishing touches for the installation of thousands of new-generation centrifuges at the cavernous facility -- machines that can produce enriched uranium much more quickly and efficiently than its present machines.
While saying that the electrical circuitry, piping and supporting equipment for the new centrifuges was now in place, the diplomats emphasized that Tehran had not started installing the new machines at its Fordo facility and could not say whether it was planning to.
Still, the senior diplomats -- who asked for anonymity because their information was privileged -- suggested that Tehran would have little reason to prepare the ground for the better centrifuges unless it planned to operate them. They spoke in recent interviews -- the last one Saturday.
The reported work at Fordo appeared to reflect Iran's determination to forge ahead with nuclear activity that could be used to make atomic arms despite rapidly escalating international sanctions and the latent threat of an Israeli military strike on its nuclear facilities.
Fordo could be used to make fissile warhead material even without such an upgrade, the diplomats said.
They said that although older than Iran's new generation machines, the centrifuges now operating there can be reconfigured within days to make such material because they already are enriching to 20 percent -- a level that can be boosted quickly to weapons-grade quality.
Their comments appeared to represent the first time anyone had quantified the time it would take to reconfigure the Fordo centrifuges into machines making weapons-grade material.
In contrast, Iran's older enrichment site at Natanz is producing uranium at 3.4 percent, a level normally used to power reactors. While that too could be turned into weapons-grade uranium, reassembling from low- to weapons-grade production is complex, and retooling the thousands of centrifuges at Natanz would likely take weeks.
The diplomats' recent comments came as International Atomic Energy Agency inspectors are scheduled to visit Tehran today. Their trip -- the second this month -- is another attempt to break more than three years of Iranian stonewalling about allegations that Tehran has -- or is -- secretly working on nuclear weapons that would be armed with uranium enriched to 90 percent or more.
Diplomats accredited to the IAEA expect little from that visit. They told the AP that -- as before -- Iran was refusing to allow the agency experts to visit Parchin, the suspected site of explosives testing for a nuclear weapon and had turned down other key requests made by the experts.
Iranian officials deny nuclear weapons aspirations, saying the claims are based on bogus intelligence from the United States and Israel.
Meanwhile, Israeli Defense Minister Ehud Barak called for "tight, ratcheted-up" sanctions against Iran to force the country to curb its nuclear ambitions, and said the political process had further to go before a military strike.
"We're still in the sanctions stage and we expect them to become even more tight," Barak said at a press conference Saturday in Tokyo at the end of a four-day visit. "I think there is consensus in most capitals of the world that Iran should not be allowed to turn into a nuclear military power."
Action against Iran's nuclear facilities must be considered before the country achieves "the same kind of immunity as Kim Jong Il," Barak said, referring to the late North Korean leader who defied pressure to abandon a nuclear weapons program.