Iran has submitted documents linked to its past nuclear activity, the UN's atomic watchdog has confirmed, a key condition of a probe into suspected efforts to create nuclear arms.

The International Atomic Energy Agency (IAEA) signed a "roadmap" with Iran in July to investigate its nuclear programme, as part of an overall accord with major world powers.

The historic deal is aimed at curbing Iran's nuclear activity in exchange for relief on painful economic sanctions.

The IAEA said Iran had met a key deadline by handing over the papers on Saturday.

"Iran... provided the IAEA with its explanation in writing and related documents as agreed in the roadmap for the clarification of past and present outstanding issues regarding Iran's nuclear programme," the agency said in a brief statement published Saturday.

A senior Iranian official also confirmed that the documents had been submitted.

"We have achieved our commitments as part of the deadline set out in the agreement," said Behrouz Kamalvandi, the spokesman of Iran's Atomic Energy Organisation.

The IAEA is to issue a report on its investigation by December 15.

The agency has long sought to probe allegations that at least until 2003 Iran's nuclear programme had "possible military dimensions" -- that it conducted research into making a nuclear bomb.

Iran has always rejected the allegations as based on faulty intelligence provided by its enemies to a gullible and biased IAEA, and a probe has been stalled since last year.

A particular sticking point in the probe had been the IAEA's desire to inspect military sites where these suspicious activities may have taken place, such as Parchin.

But following the deal reached in July with the so-called P5+1 -- Russia, France, China, Germany, Britain and the United States --Iran granted the IAEA tightly-controlled "managed access" to its military bases.