The head of the UN atomic watchdog has said Iran’s new leadership has indicated a willingness to address concerns regardless of progress in parallel talks with world powers.

The International Atomic Energy Agency said this week that it held “productive” talks with President Hassan Rouhani’s Government, which come as Iran conducts separate negotiations with the US and five other nations over its nuclear programme.

In a break with Iran’s past statements, Yukiya Amano, Director-General of the IAEA, said Rouhani’s team has not tied cooperation with the Vienna-based agency to the political talks — in which Tehran is seeking relief from crippling US-led sanctions.

“I can tell you that after the coming of President Rouhani, we have had a number of contacts with them.. but we haven’t heard this linkage,” Amano said at the Woodrow Wilson International Center for Scholars in Washington.

Asked whether this marked a significant change, Amano said: “I think so. There is some substance in the new proposal by Iran.”

Rouhani, who swept to power in June on promises to repair Iran’s troubled economy and ease its political isolation, has called for a quick agreement to end concerns that the clerical regime’s uranium work is aimed at building a nuclear bomb.

The IAEA, which meets again in Tehran on November 11, and the six major powers, which meet Iran again in Geneva on November 7-8, have declined to describe Iran’s proposals in public while negotiations are underway.

For the IAEA, one sticking point is the agency’s hope of investigating allegations that Iranian scientists conducted experiments aimed at developing a nuclear arsenal before 2003 and possibly since.

Iran has denied the charges, saying that purported evidence comes from faulty intelligence by the likes of the CIA and Israel’s Mossad that Tehran has not been allowed to see.

Amano said the IAEA “would like to clarify the present and past activities” of Iran but declined to say whether he expected Tehran to allow a more intrusive probe.

While President Barack Obama’s administration has voiced guarded optimism about reaching a peaceful settlement with Iran, Israeli Prime Minister Benjamin Netanyahu has denounced Rouhani as a “wolf in sheep’s clothing” and not ruled out a military strike.