The International Atomic Energy Agency (IAEA) is due to publish a report this week on the matter, which could allay remaining concerns on Iran's intentions as part of a deal between world powers and Tehran.

It could provide for a lifting of sanctions against the Islamic Republic in exchange for restrictions on its nuclear program - but that could be scuppered if any of the parties, including France, are not satisfied.

A clear verdict that weapons-related work occurred would make it difficult for the deal to proceed, but diplomats have said for weeks that they do not expect it to be clear-cut.

France, which was deemed to have had the toughest stance during talks between the major powers and Iran, was especially concerned during negotiations that the issue of the past would not be correctly addressed after a final accord was agreed.

"France will with interest become aware of this report this week," Foreign Ministry spokesman Romain Nadal said in a daily news briefing. "We are expecting that the IAEA provides with the necessary detail all the information it possesses."

IAEA chief Yukiya Amano said on Thursday the report would not reach a definitive conclusion about the final assessment of possible military dimensions, or PMD, file, which may not be enough for France.

In November 2011, the IAEA issued an annex to a regular report on Iran, listing 12 issues that could indicate Iran might have had a nuclear weapons program.

Iran denies these allegations, but the IAEA, which says it takes no information at face value, has described the intelligence from its member states which formed the basis of the PMD file as "overall credible".