The U.N. nuclear agency will be able to deliver an assessment of the suspicions that Iran worked on atomic weapons by Dec. 15, as planned, it said Thursday.

The agency said in a statement that it has completed a series of meetings with Iranian officials focused on "ambiguities" in information previously provided by Tehran, allowing the IAEA to deliver the report in the timeframe set out in a deal between Iran and six world powers.

Iran says it never worked on nuclear weapons, and it is unclear whether the agency will be able to make a definite ruling on the allegations. Diplomats have previously said that the report may confirm only that Iran provided answers to all IAEA questions without saying outright that the answers confirmed or disproved the suspicions.

But they say an IAEA ruling that Iran has cooperated could allow the United States and its allies to accept an end to decade-long attempts to probe the allegations.

Washington and its allies insist they have evidence of past nuclear arms work by Tehran. But the diplomats say the U.S. is ready to accept a vaguer report than it would normally demand because seeking further clarity would lead to deadlock with Iran that would jeopardize the larger agreement.

That overarching deal was reached July 14, but the date for its adoption is this Sunday. That makes IAEA confirmation that Iran met the deadline before Sunday important.

Formal adoption clears the way for the start of implementation of the actions set out in the deal — cuts in Iran's nuclear program in exchange for lifting of economic sanctions that have crippled Iran.

Officials from Iran and the six nations — the United States, Russia, China, Britain, France and Germany — are meeting in Vienna Monday to discuss those next steps.