The negotiations in Vienna are the first between Iran and the agency in three months. They last met in Tehran in February, CNN reported.
The aim of the current meeting is to "devise a framework for answering questions about Tehran's nuclear energy program," Iran's state-run Press TV quoted the Iranian ambassador to the IAEA, Ali Asghar Soltanieh, as saying.
Iran denies allegations that it is developing weapons and has said the program is solely directed toward developing civilian nuclear energy.
However, Western powers have said they believe Iran has evaded international inspections and is intent on developing nuclear weapons.
Further discussions are set to be held at the end of May.
The talks have involved the five permanent members of the United Nations Security Council -- the United States, France, Russia, China, and Britain -- as well as Germany, referred to as the P5+1.
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