A senior United Nations official in charge of the probe into Iran’s nuclear program said that he would provide a final report on the issue by next week, but warned he could not guarantee that Tehran’s greatly reduced program was meant completely for peaceful purposes.

International Atomic Energy Agency (IAEA) chief Yukiya Amano said he was “not in a position to provide credible assurance about the absence of undeclared nuclear material and activities in Iran,” and thus cannot conclude that “all nuclear material in Iran is in peaceful activities,” according to the Associated Press (AP).

Speaking to the IAEA’s 35-nation board, Amano said Tehran would soon enact an agreement that would give the U.N. agency greater inspection rights to military bases suspected to have conducted research into developing nuclear weapons.

"Next week, I expect to provide my final assessment on all past and present outstanding issues," Amano said in Vienna, AP reported. 

Access to Iranian military bases such as the Parchin military base has been a long-standing issue between the U.N. nuclear watchdog and Iran. A 2011 IAEA report alleged Iran was carrying out high-explosives tests at the Parchin base to work out how to put atomic material inside a missile warhead.

Iran maintains that the claims are based on faulty intelligence provided by its enemies to IAEA, and that all its nuclear activities are exclusively for peaceful uses. The country agreed to provide information and access to sites including Parchin. Under a deal struck with Western powers in July, Iran agreed to scale back its nuclear program in exchange for removal of crippling economic sanctions.

Earlier this month,  Iranian media outlets reported that the country had begun dismantling some 10,000 centrifuges in the Natanz enrichment facility.