Diplomats say the U.N.'s atomic agency will be reporting a standstill in attempts to probe allegations Iran worked on nuclear arms, in an assessment later Friday.

The International Atomic Energy Agency reports regularly on Iran's nuclear program. But the upcoming summary is particularly important because its investigation figures in an emerging deal meant to restrict Tehran's nuclear activities in exchange for sanctions relief.

The United States and its allies insist the IAEA must rule on the allegations based on its probe as part of any Iran-six world power accord. Iran denies any work — or interest — in nuclear arms and says the accusations are based on phony evidence from Israel, the U.S. and other adversaries.

The diplomats demanded anonymity because they are not authorized to discuss the confidential report.