Yukiya Amano, head of the International Atomic Energy Agency, is set to meet Thursday with Iranian President Hassan Rouhani in Tehran in a bid to reach agreement on outstanding verification issues as negotiators work on a nuclear deal.

"Discussions are expected to address ongoing cooperation between the IAEA and the Islamic Republic of Iran under the Framework for Cooperation, and how to accelerate the resolution of all outstanding issues related to Iran's nuclear program, including clarification of possible military dimensions," the IAEA said in a statement on Wednesday.

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Iran is required by U.N. Security Council resolutions to give the IAEA a full accounting of its past work involving nuclear weapons, but has not yet done so. The issue has dogged international negotiations in Vienna on limiting Iran's nuclear program to peaceful purposes.

Neutral experts have said a full accounting of any past military work is essential for setting the baseline for verification of any deal, and Iran agreed to address the IAEA's concerns in the framework for a final deal announced April 2.

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Politically this is a crucial issue for President Obama. Reports that U.S. negotiators were willing to accept an agreement that did not require Iran to give a full accounting of past military work provoked a backlash from lawmakers, who will have a chance to review any deal once it is completed.

Negotiators have set a July 7 deadline to complete the deal.