Despite Western nations tightening the screws on Iran, a top aide to President Mahmoud Ahmadinejad says increasingly tough sanctions have failed.

On the eve of fresh negotiations with Western powers tentatively set for December 5, Ahmadinejad confidant Mojtaba Samareh Hashemi said it was time for them to "stop fooling themselves" over the effectiveness of measures designed to pressure Iran into abandoning its uranium enrichment program.

Banning Iranian ships from European ports, a fuel blockade against Iran Air, growing financial restrictions and other punitive measures have had "no noticeable effect," he added in an interview with The Washington Post conducted Monday and published Wednesday.

"The delay in the negotiations has been a good opportunity for the other side to realize the effects of its political decisions."

He also claimed the failure of sanctions had prompted the West to relaunch the long-stalled talks, a direct contradiction of the US position.

Iran is under four sets of UN Security Council sanctions over its refusal to suspend uranium enrichment, which is at the center of fears about Tehran's atomic ambitions. It has also faced military threats and alleged technological attacks on its controversial nuclear program.

Tehran and the so-called P5+1 that groups the United States, Russia, China, France, Britain and Germany have agreed to return to the negotiating table for the first time since October 2009 for a meeting tentatively scheduled to take place next month in Geneva.

Samareh Hashemi's comments came as the UN atomic watchdog found Tuesday that Iran was still uncooperative after nearly eight years of attempting to determine if its nuclear program is military or, as Tehran insists, peaceful in its objectives.

The International Atomic Energy Agency's restricted report demands full access to Iran's nuclear facilities, equipment and related documents, and said its uranium enrichment activities inexplicably came to a halt at least one day earlier this month, amid rumors it encountered technical problems.

If Western powers do not respond to Iran's request to broaden discussions beyond its nuclear program to also discuss Israel's alleged nuclear weapons stockpile and declare they are committed to nuclear disarmament, Iran would be forced to take a harder position, Samareh Hashemi said.

It would mean "they have not chosen the path of friendship," he added.

"Not answering these questions will mean they have decided not to commit to nuclear disarmament and support the Zionist regime being armed with nuclear weapons."

But the 52-year-old foreign policy expert also said Iranian negotiators will consider proposed changes to a nuclear fuel swap proposal that failed at the talks last year.

"It is not like we don't listen to new proposals," he said, adding that no deal would stop Iran from producing higher-enriched uranium, up to 19.75 percent, to run its medical reactor.

The aide also dismissed suggestions by US Defense Secretary Robert Gates last week that the sanctions were hitting Iran hard and causing a rift between Ahmadinejad and the country's supreme leader, Ayatollah Ali Khamenei.

"Such statements are uninformed and illustrate the wishful thinking of this American secretary of defense," Samareh Hashemi said. "It is surprising a person at such a high level in the US government can be so uninformed."