A series of unanswered questions on Iran’s program to enrich uranium for bombs and power will be raised today as the board of the International Atomic Energy Agency meets in Vienna.

Those questions may lead the U.N. atomic watchdog to confirm what some Western intelligence agencies concluded long ago: that Iran has been concealing a nuclear weapons program among the nuclear research facilities it declared in 2003 to the IAEA.

That is what the London Daily Telegraph reports today in a story disclosing a secret underground nuclear weapons project code-named “Zirzamin 27.”

Citing experts at the IAEA, reporter Con Coughlin writes, “Concerns over activity at Zirzamin 27 will be raised at this week’s meeting of the agency’s board of governors in Vienna.” He says the project, which means “basement 27” in Farsi, suggests the military program is located in a bunker deep underground and that the number 27 refers to the number of years since the 1979 Islamic revolution.

Iran’s president, supreme leader, and foreign minister have all insisted that their enrichment activities are not only permissible under the nuclear nonproliferation treaty but intended to power the economy of the world’s third largest exporter of petroleum. Nonetheless, many Western nations have cast a suspicious eye toward Iran since it declared in 2003 a hitherto secret enrichment program at Natanz and other sites. In 2004, IAEA inspectors tried to visit a military lab at Lavizan, where traces of enriched material was found on equipment, only to find the facility razed to the ground and its activities “relocated.”

In his report to the IAEA board dated June 8, the director general, Mohamed ElBaradei, reported he could not say whether Iran was undertaking more undeclared nuclear research. His doubts stem in part from his failure to receive credible answers from the Iranians on the source of contamination found on equipment and the “scope and chronology of Iran’s centrifuge enrichment program.”

Iran’s case is also not strengthened after its envoy to the IAEA offered to allow unannounced inspections only if Iran’s nuclear enrichment program was not taken to the U.N. Security Council.

The outstanding questions for the Islamic Republic come as its leaders are mulling over a new offer from America, China, France, Germany, Russia, and Britain meant to entice them to suspend enrichment in exchange for a light water nuclear reactor, trade benefits, and further diplomatic acceptance.

Should the IAEA present compelling evidence that Iran has been operating a secret nuclear military program, the progress toward settling Iran’s fate through negotiations may soon turn toward a momentum for diplomatic confrontation.

Thus far in Washington, President Bush and Condoleezza Rice have described the American offer to join nuclear talks as Iran’s last chance to settle the matter before economic and diplomatic sanctions are imposed. They have not ruled out military action.

So far this month, while Iran’s leaders have toned down their defiant rhetoric, when the president denounced the American offer as “propaganda,” their actions continue to be hostile toward the West. On Friday, Reuters reported that the IAEA found last week that the Iranians had begun a fresh round of uranium conversion, the process of distilling the element in its yellowcake form to the UF6 gas suitable for centrifuges.

The New York Sun reported last week that the great powers have yet to reach an agreement on how a suspension of enrichment is to be defined. America is pressing for an encompassing definition that would include the conversion of yellowcake into UF6 gas, while Russia and the IAEA director general have pressed to allow some of this conversion for research purposes.