The International Atomic Energy Agency (search), the U.N.'s nuclear watchdog, has found more traces of weapons-grade, highly enriched uranium in Iran, Fox News has confirmed.
Diplomats said new remnants were found at the Kalay-e Electric Co. (search) on the southern outskirts of Tehran.
The IAEA would not confirm the report nor would it comment on ongoing inspections of Iran's nuclear program.
"We are not commenting on the results of samples or ongoing inspections," said IAEA spokesman Mark Gwozdecky.
But IAEA chief Mohamed ElBaradei (search) gave an interview with a National Public Radio journalist on Wednesday, in which he confirmed the results of the latest field samples taken in Iran had come back.
"There will be universal condemnation if they continue with a nuclear program," President Bush told reporters Thursday. "People understand the danger of Iran having a nuclear weapons program."
Bush said he would discuss the matter this weekend with Russian President Vladimir Putin (search), who will visit Bush at Camp David.
The Bush administration said on Thursday that Iran had "one last chance" to comply with nuclear safeguards and threatened to take the issue to the U.N. Security Council.
"These are part of a long-standing pattern of evasions and deception to disguise the true nature and purpose of Iran's nuclear activities," White House spokesman Scott McClellan told reporters earlier. "The international community is expressing the same concern that we have been expressing."
Earlier this year, the U.N. inspectors found traces of enriched uranium at Natanz (search), another nuclear site in Iran, raising suspicions that Iran had been secretly purifying uranium for a nuclear-weapons program.
Tehran maintains that its nuclear program is peaceful and is aimed at producing energy. Tehran has blamed the Natanz find on imported machinery it says it purchased abroad on the black market in the 1980s.
Iran had insisted that its enrichment centrifuges were never tested live, meaning with nuclear material. Iran has always said it only wants to produce low-enriched uranium, unusable in bombs.
The United States and its allies have insisted the nuclear program is for weapons.
Iranian Foreign Minister Kamal Kharrazi said outside the U.N. General Assembly in New York on Thursday that his country was able to enrich its own uranium but does not have the technology to develop nuclear weapons.
A diplomatic source told Fox News that the latest find is not surprising.
Iran tested equipment at Kalay-e that was later installed at the uranium enrichment plant at Natanz, where the first highly enriched uranium find was made.
But the question remains whether Iran lied about not using nuclear material in its testing, or if the uranium traces were present on the equipment when it was purchased. Fox News has learned the contaminated equipment was likely purchased from Pakistan.
But another Western diplomat told Reuters, "this finding may actually raise even more questions about the discovery of enriched uranium."
A team of inspectors from the agency is scheduled to leave for Tehran on Sunday, for "an intensive work program over the next five weeks involving more or less a continuous presence in Iran," Gwozdecky said.
While on assignment, officials said they are constantly taking field samples.
Iran has until Oct. 31 to prove to the IAEA that it has no secret nuclear-weapons program, as the United States alleges.
In imposing the deadline, the IAEA has also urged countries that have sold equipment to Iran to come forward. Iran says it has kept no lists of suppliers, but diplomats have told The Associated Press that while some of the equipment is consistent with Pakistan's nuclear program, other components appear to have come from Western European companies.
The next IAEA board of governors meeting will be held in Vienna on Nov. 20. If Iran is found to be violating the treaty banning the spread of nuclear weapons, the U.N. Security Council could be asked to get involved. That could result in economic and political sanctions.
Iran had recently indicated it might be willing to negotiate with the IAEA, but its envoy to the Vienna-based agency, Ali Akbar Salehi, said Tehran would scale back cooperation, indicating Tehran would cooperate only to the point it was bound to under agreements with the agency.
"We have decided to fulfill our obligation under the nuclear Non-Proliferation Treaty and not beyond that," Salehi said Monday. "It doesn’t mean that we are rejecting the additional protocol or are not prepared to talk on that."
U.S. officials said the nuclear situation should not be ignored and any sign of banned activity needed to be taken seriously.
"I think any proliferation of nuclear weapons or nuclear materials that could be producing nuke weapons is a serious problem," Sen. John Corzine, D-N.J., told Fox News on Thursday.
Corzine said, "it's interesting" that it was an international agency that made the discovery.
"It speaks to how important it is that we have strong and capable international institutions the United States needs to be supporting," he commented in an oblique reference to the White House's lack of enthusiasm for working with the United Nations and signing global treaties.
Sen. Norm Coleman, R-Minn., stressed that Iran needs to be taken seriously.
"They're sending rather mixed signals, but bottom line, Iran supports terrorists," Coleman said, referring to Tehran's strong ties to Lebanese Hezbollah (search). "They're a danger and they have to be dealt with."
Sen. Jim Talent, R-Mo., a member of the Senate Armed Services Committee, said there's no doubt in his mind Iran is moving forward with its nuclear weapons program.
"These things happen over and over again," Talent said. "This time, I hope the international community acts decisively. We have to tell them we need open and immediate inspections ... or the results are going to be serious. We need to act together as an international community."
In recent weeks, agency inspectors had been given access to sites not covered in the agreements, although the IAEA had complained of delays that in some cases appeared to have served to give authorities a chance to cover their tracks.
In August, Iran allowed inspectors to visit Kalay-e after they were turned away two months before when they came to take environmental samples. Iran allegedly had tested centrifuges, which are used to enrich uranium, at the site.
At an IAEA board meeting earlier this month, chief U.S. delegate Kenneth Brill focused on a report outlining discrepancies between past Iranian statements on the nature of Tehran's nuclear programs and IAEA findings of weapons-grade enriched uranium and other evidence of a weapons program.
"The United States believes the facts already established would fully justify an immediate finding of noncompliance by Iran," Brill said. Still, he said, the Americans were ready to give Iran "a last chance to drop its evasions" before pushing for Security Council involvement.
Fox News' Wendell Goler, Liza Porteus and The Associated Press contributed to this report.