VIENNA (AP) — The U.N. nuclear agency prepared Tuesday to close the books on a decade-long probe of allegations that Iran worked on atomic arms, despite acknowledgement by its head that his investigation remains incomplete.

The probe has to be formally closed as part of a deal between Iran and six nations to crimp present Iranian nuclear programs that could be used to make such weapons, in exchange for the removal of economic sanctions.

Ahead of adoption of a resolution ending the investigation, Yukiya Amano of the UN.'s International Atomic Energy Agency told the agency's 35-nation board that his investigation could not "reconstruct all the details of activities conducted by Iran in the past."

At the same time he repeated an assessment he made last month, that Iran worked on "a range of activities relevant" to making nuclear weapons, with coordinated efforts up to 2003 tapering off into scattered activities up to 2009.

Despite Iranian denials, the United States and its allies continue to believe that Tehran did such work. But their overriding interest is moving on to implementing the July 14 deal that focuses on limiting Iran's nuclear activities for more than a decade — a plan that depends on shutting down the probe.

An EU statement obtained before delivery reflects the will to move on. Unlike previous statements, it avoids criticism of Iran over its alleged weapons research and development program, saying only "we note" the IAEA conclusion.

The resolution on ending the investigation was drawn up by the United States and the other nations that negotiated the July 14 deal with Iran — Russia, China, Britain, France and Germany

Once approved, it opens the way for implementation of that deal, formally expected next month. Once the IAEA confirms that Iran has modified or cut back on programs and activities that could be re-engineered to produce the fissile core of nuclear weapons, individual and international sanctions imposed on Iran over its nuclear program will be lifted.