Iran has agreed to give U.N. inspectors access to a huge military site that the United States alleges is linked to a secret nuclear weapons program, the head of the International Atomic Energy Agency (search) said Wednesday.

IAEA Director General Mohamed ElBaradei (search) told The Associated Press he expected his experts to visit the Parchin site "within days or weeks."

The agency has been pressing Tehran for months to be allowed to inspect the Parchin (search) military complex, used by the Iranians to research, develop and produce ammunition, missiles and high explosives.

In leaks to media last year, U.S. intelligence officials said that a specially secured site on the Parchin complex, about 30 kilometers (20 miles) southeast of Tehran, may be used in research on nuclear arms, specifically in making high-explosive components for use in such weapons.

The IAEA has not found any firm evidence to challenge Iranian assertions that its military is not involved nuclear activities.

But an IAEA report in October expressed concern about published intelligence and media reports "relating to dual use equipment and materials which have applications ... in the nuclear military area."

Diplomats said that phrasing alluded to Parchin.

Iran has been the main focus of the IAEA since mid-2002, after revelations of two secret nuclear facilities — a uranium enrichment plant at Natanz and a heavy water production plant near Arak.

That led to a subsequent IAEA investigation of what turned out to be nearly two decades of covert nuclear activities, including suspicious "dual use" experiments that can be linked to weapons programs.

As part of his probe, ElBaradei has produced a series of reports detailing the progress of investigations for guidance by the IAEA board on deciding what to do about Iran's nuclear activities.

Despite the revelations of "dual-use" activities and a large-scale uranium enrichment program that could be used to make nuclear weapons, ElBaradei has stopped short of declaring Tehran in breach of the Nuclear Nonproliferation Treaty.

That has fed U.S. frustrations. Insisting that Iran has violated the treaty, Washington has repeatedly urged the board to ask the U.N. Security Council to take Tehran to task.

Senior U.S. officials have blamed ElBaradei for the board's refusal to do so, suggesting he is too soft on Iran and that they will fight his attempts this year to gain re-election for a third term as IAEA head.

ElBaradei said that he will "continue to keep the board updated" on Iran. But he told the AP that he may decide not to produce a new report on Tehran's nuclear activities for the next board meeting in March, adding that he hoped to reduce the Iran file to "routine reporting" over the next six months.

Such steps would fuel U.S. anger by effectively suggesting that the probe of Tehran's nuclear activities was no longer important enough to warrant special consideration.

ElBaradei's agency is monitoring an Iranian commitment made in November to suspend uranium enrichment activities that could be used to make the core for nuclear weapons. He said Tuesday that there had been no violations of that agreement.