Dr. Mohammed ElBaradei, director general of the International Atomic Energy Agency, spoke in Tehran following talks with Iranian officials over the recently-revealed facility that has caused consternation around to world over the extent and purpose of Iran's nuclear program.
"I see that we are at a critical moment, I see that we are shifting gears from confrontation into transparency and cooperation," said ElBaradei as he announced the new inspection date.
"I hope and trust Iran will be helpful with our inspectors so it is possible for us to be able to assess our verification of the facility as early as possible," he added, while sitting next to Ali Akbar Salehi, the head of Iran's nuclear program.
The news came shortly after The New York Times reported on its Web site Saturday night that, according to a confidential analysis by the U.N.'s nuclear regulatory agency, Iran has obtained "sufficient information" required to design and manufacture an atomic bomb.
While IAEA staff members declare their findings are tentative and require further investigation and confirmation, their conclusions, said the Times, go further than the public statements of the United States and other governments.
The leaked IAEA report, on top of ElBaradei's arrival in Tehran to arrange inspections of recently-revealed nuclear facility in Qom, "is sure to put pressure on the Obama administration to require Iran to disclose the bigger picture of all its uranium enrichment facilities and allow for inspection," said CBS News Foreign Affairs Analyst Pamela Falk, based at the U.N., "and that runs counter to the denials of secrecy coming from Tehran."
The revelation that Iran has been building a new nuclear plant near the holy city of Qom has heightened the concern of the U.S. and many of its allies, which suspect Tehran is using a civilian nuclear program as a cover for developing a weapons-making capability.
Iran denies such an aim, saying it only wants to generate energy.
Suspicion that Iran's newly-revealed nuclear site is meant for military purposes was heightened by its location - at least partly inside a mountain and next to a military base.
President Obama and the leaders of France and Britain accused Iran of keeping the construction hidden from the world for years. The U.S. president said last month that Iran's actions "raised grave doubts" about its promise to use nuclear technology for peaceful purposes only.
"Mr. Obama made a great mistake," said President Mahmoud Ahmadinejad, "a historic mistake."
at a landmark meeting with six world powers near Geneva on Thursday that put nuclear talks back on track and included the highest-level bilateral contact with the U.S. in three decades.
"The major breakthrough from the first diplomatic talks between Iran and the U.S. in decades, is that the Iranian government will allow international inspectors into the newly-discovered nuclear facility in Qom, in Iran," Falk said.
"Perhaps buying time, or perhaps heading into a better period of U.S.-Iran relations, Iran's Foreign Minister Manouchehr Mottaki told reporters here at the U.N. that the talks in Geneva were constructive, that they would continue, and that Iran would like a summit level meeting with world powers," said Falk.
Iranian officials argue that under IAEA safeguard rules, a member nation is required to inform the U.N. agency about the existence of a nuclear facility six months before introducing nuclear material into the machines. Iran said the new facility won't be operational for 18 months, and so it has not violated any IAEA requirements.
"Mr. Obama made a great mistake, a historic mistake," Iranian President Mahmoud Ahmadinejad said on Saturday, claiming that instead of trying to keep the site secret, Iran willfully revealed its existence one year before it was legally required to, "out of respect for law."
"Later it became clear that (Obama's) information was wrong and that we had no secrecy," Ahmadinejad said. White House spokesman Tom Vietor said the administration had no comment on Ahmadinejad's remarks.
"We need transparency on the part of Iran and we need cooperation on the part of the international community," he said.
But in Geneva earlier this week, there appeared to be historic progress in talks between the Iranians and 6 world powers.
The Iranians not only said IAEA inspectors could visit the secret plant within 2 weeks, they also agreed in principle to cooperate with Russia and France on a sensitive uranium enrichment project, and announced they'd be back to negotiate further.
The deal that was struck in Geneva on Thursday represents progress of sorts, said CBS News correspondent Elizabeth Palmer. At least it shows the Iranians are willing to talk about their secretive nuclear program, but there's no doubt the really hard bargaining is about to begin.
Some analysts think the regime is counting on nuclear negotiations with the West to shore up support at home for a government whose legitimacy is not recognized by millions of its own citizens, after weeks of extreme violence following Iran's June elections.
"The message that the regime wanted to send back to Iran [is] that, no matter what you think or how we are treating you, at the end of the day the international community will speak to us and not support you," said Nazenin Ansari, Diplomatic Editor of Kayhan Newspaper.
Palmer said Western diplomats know the nuclear talks - due to start again before the end of the month - might send this signal to a discouraged reform movement.
But at the moment, they say, the priority is to make sure Iran does not develop a nuclear bomb.
Also on Sunday, ElBaradei discussed a plan to allow Russia to take some of Iran's processed uranium and enrich it to higher levels to fuel a research reactor in Tehran.
He said that there would be a meeting Oct. 19 in Vienna with Iran, the U.S., France and Russia to discuss the details of that agreement.
The Obama administration, together with the U.S. Congress, is drawing up plans for tough new sanctions if the talks with Iran show signs of faltering. Obama said the new penalties could target Iran's energy, financial and telecommunications sectors.
A congressional committee will hold a hearing Tuesday on the possibility of expanding sanctions to cover a wider range of financial transactions, including a new ban on exporting refined petroleum to Iran.