VIENNA — Iran on Saturday gave the U.N. nuclear agency documents linked to the agency’s probe of allegations that Tehran tried to develop atomic arms, along with a confidential explanation that is unlikely to veer from previous Iranian denials of work on such weapons.

Announced by the U.N’s International Atomic Energy Agency, the handover meets a key deadline Iran has committed to as part of its overarching deal with six world powers promising Tehran sanctions relief in exchange for nuclear concessions.

The July 14 deal’s main focus is curbing Iran’s present nuclear program that could be used to make weapons. But a subsidiary element obligates Tehran to cooperate with the IAEA in its probe of the allegations.

The investigation has been essentially deadlocked for years with Tehran asserting the allegations are based on false intelligence from the United States, Israel and other adversaries. But Iran and the U.N. agency agreed last month to wrap up the investigation by December, when the IAEA plans to issue a final assessment on the allegations. Saturday was the target date for Tehran to provide the agency documents related to the probe and its version of what they mean.

Both Iran and the IAEA were upbeat when announcing the agreement last month. But Western diplomats from IAEA member nations who are familiar with the probe are doubtful that Tehran will diverge from claiming that all its nuclear activities are – and were – peaceful, despite what they say is evidence to the contrary.

They say the agency will be able to report in December.