The UN nuclear monitoring agency on Wednesday announced a "milestone" agreement with Iran that aims to provide answers about allegations Teheran tried to develop nuclear weapons under cover of a peaceful atomic program. International Atomic Energy Agency spokeswoman Melissa Fleming divulged no details in a brief statement about the deal. But IAEA chief Mohamed ElBaradei called the agreement "a milestone" that - if successful - should signal the end of his organization's years of attempts to probe Teheran's secretive nuclear program. "An agreement was reached during the meetings in Teheran on a process that aims to clarify the so-called alleged (nuclear weapons) studies during the month of May," Fleming said in a statement from the Vienna-based agency. She was alluding to talks Monday and Tuesday between senior Iranian officials and IAEA Deputy Director General Olli Heinonen. ElBaradei, in Sarajevo before collecting an award from a Bosnian university, said he was hopeful that by the May deadline "we will be in a position to get the explanation and clarification from Iran as to these alleged studies," adding: "This, in my view, is a positive step." He called the issue "the only remaining topic for us to investigate about past and present Iran nuclear activities" - a statement sure to be challenged by the US and other nations suspicious that Teheran may be hiding an undeclared nuclear program from the agency. Still, any agreement by Iran to at least further discuss the allegations is a positive sign. On April 13, Gholam Reza Aghazadeh, the head of Iran's nuclear program, abruptly canceled a meeting with ElBaradei. The Aghazadeh-ElBaradei meeting had been considered a test of whether Iran will continue to stonewall the IAEA in its attempt to investigate the alleged military programs. Intelligence received by the IAEA from the US 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 -drew up blueprints on refitting missiles to allow them to carry nuclear warheads -was researching construction of an underground site that apparently could be used for test nuclear explosions -ordered "dual use" equipment from abroad that could be part of a nuclear weapons program, and, -appointed officials to work on these projects who were also active in Iran's civilian nuclear programs. Additionally, Iran possesses diagrams showing how to mold uranium metal into the shape of warheads. Teheran has denied ever trying to make nuclear weapons and has rejected the evidence as fake. But US intelligence agencies say Teheran experimented with such programs until 2003, and other countries believe it continued past that date. Iran is under three sets of UN 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. "But if you resort to deception and seek to impose (your demands), ... the Iranian nation will heavily slap bad-wishers in the mouth."