The head of the UN nuclear agency urged Iran on Monday to sign a deal allowing greater clarity on its disputed nuclear drive and announced that new talks with Tehran would be held this week.
At the start of a week-long meeting of the International Atomic Energy Agency's board of governors in Vienna, Yukiya Amano "invited" Iran to sign an agreement to give the agency access to sites, documents and people related to its nuclear programme.
This would include the Parchin military base near Tehran, where the IAEA believes suspicious explosives testing has been carried out.
"If we do not have access to the Parchin site or other people, information and sites, then... we cannot give assurance that all the activities in Iran have peaceful purposes," Amano told journalists.
"And that is not in the interest of Iran, nor the IAEA nor the international community. So what I expect is proactive cooperation from Iran and to clarify these issues through IAEA verification."
A new round of talks between the agency and Iran -- likely to involve IAEA chief inspector Herman Nackaerts and deputy director general Rafael Grossi, as well as Iran's envoy to the agency Ali Asghar Soltanieh -- would take place Friday in Vienna, he added.
After a visit to Tehran on May 21, where he met with Iran's chief nuclear negotiator Saeed Jalili, Amano said Iran and the IAEA could sign an accord "quite soon."
"I was assured that an agreement... would be expedited," Amano said Monday.
"I think we need to hope that the Structured Approach agreement will be signed as soon as possible," he added, noting that differences between the parties had "narrowed."
Soltanieh meanwhile told national news agency IRNA that after Amano's visit, "a new chapter of cooperation between the Islamic Republic of Iran and the agency has started".
The IAEA has been seeking to visit Parchin for months but has been refused access by Tehran, which insists the site is of no significance to its nuclear programme so it need not allow inspections there.
In its last report, the IAEA said new satellite imagery indicated "extensive activities" at the base, which experts saw as signs of a clean-up.
These included "the use of water, demolishing buildings, removing fences and removing soils," Amano said Monday.
"We have clear concerns that these activities may hamper our future verification activities... even though we have advanced tools" to detect nuclear materials, he added.
The closed-door IAEA meeting comes amid a flurry of international talks to try to curb what the West sees as an Iranian bid to make a nuclear bomb, claims denied by Tehran which insists its atomic programme is solely for peaceful purposes.
The so-called P5+1 -- the United States, Russia, China, Britain, France and Germany -- revived talks with Iran in Istanbul in April and met again in May in Baghdad, although little was achieved.
Iran and the six world powers are due to meet again in Moscow on June 18-19, before an EU oil embargo against Iran comes into force on July 1.
A key source of dispute has been Iran's enrichment of uranium to 20-percent purity, bringing Tehran consistently closer to producing 90-percent enriched uranium needed to make a bomb, according to Western powers.
On Sunday, Iran's supreme leader Ayatollah Ali Khamenei said claims Tehran was seeking nuclear weapons were "based on a lie" and insisted that sanctions on his country were ineffective and only strengthened its resolve.
Iran has already been subjected to four rounds of UN Security Council sanctions over its nuclear activities.
Israeli newspaper Haaretz reported on Monday that Israel and the United States were discussing a new raft of sanctions if the next round of talks between world powers and Tehran fail.
"If we don't get a breakthrough in Moscow there is no question we will continue to ratchet up the pressure," US Treasury Undersecretary David Cohen, who coordinates US sanctions policy against Iran, told the paper.