International Atomic Energy Agency (IAEA) chief Yukiya Amano says he could conclude his probe on allegations that Iran worked secretly to develop nuclear weapons by December if Tehran cooperates.
Amano said in Vienna on July 4 that "I think we can issue a report by the end of the year on the...clarification of the issues related to possible military dimensions" of Iran's nuclear program.
Iran has denied accusations it has sought to develop a nuclear bomb and has refused to give IAEA inspectors access to military sites.
Amano made his comments after returning from a trip to Iran, where he met with Iranian officials about the IAEA's need to visit military sites and to speak with Iranian scientists.
His comments on July 3 upon returning to Vienna suggested his meeting with Iranian President Hassan Rohani did not result in a breakthrough.
The United States has said the IAEA must deliver a ruling on suspicions of Iran's research into military uses for its nuclear program as part of a deal being negotiated between Tehran and six world powers to curb Iran's controversial nuclear program in exchange for relief from sanctions.
A July 7 deadline for the deal has been set.