International Atomic Energy Agency spokeswoman Melissa Fleming said in a statement that progress was made in talks Monday and Tuesday between senior Iranian officials and IAEA Deputy Director General Olli Heinonen.
The development appeared to signal some flexibility on the part of Tehran, which up to the last few days dismissed such allegations as U.S.-instigated fabrications.
Any agreement by Iran to at least further discuss the allegations is a positive sign.
Just last Sunday, Gholam Reza Aghazadeh, the head of Iran's nuclear program, abruptly canceled a meeting with IAEA chief Mohamed ElBaradei. The meeting had been considered a test of whether Iran will continue to stonewall the Vienna-based agency in its attempt to investigate the alleged military programs.
Intelligence received by the IAEA from the U.S. and other agency board member nations and the agency's own investigations suggest that Iran experimented with an undeclared uranium enrichment program that was linked to a missile project and drew up blueprints on refitting missiles to allow them to carry nuclear warheads.
The intelligence also suggested Iran was researching construction of an underground site that apparently could be used for test nuclear explosions and ordered "dual use" equipment from abroad that could be part of a nuclear weapons program.
Additionally, Iran possesses diagrams showing how to mold uranium metal into the shape of warheads.
Tehran has denied ever trying to make nuclear weapons and has rejected the evidence as fake. But U.S. intelligence agencies say Tehran experimented with such programs until 2003 and other countries believe it continued past that date.
Iran is under three sets of U.N. Security Council sanctions for its refusal to suspend uranium enrichment and meet other council demands designed to ease fears its civilian nuclear program is a cover for attempts to make atomic arms.
While the Islamic Republic says its enrichment program is meant to generate nuclear fuel, its past nuclear secrecy and defiance of the Security Council are fueling fears it could decide to use the technology to make the weapons-grade enriched uranium used for the fissile core of nuclear arms.
In Iran on Wednesday, President Mahmoud Ahmadinejad warned that those imposing pressure on Iran on enrichment will suffer even as he said that his country remained prepared to discuss its nuclear activities with the outside world.
"The enemies should know that the Iranian nation is for logic and dialogue with any of you if the criteria is justice and respect," Ahmadinejad told thousands of Iranians in Hamedan, western Iran.