Secretary-General Ban Ki-moon said the initiative by Brazil and Turkey regarding nuclear fuel for an Iranian reactor could be a positive step, and underscored the need for bolstered transparency to help resolve concerns over Tehran's nuclear programme.
His comments come on the same day that members of the Security Council are holding closed-door talks on imposing new United Nations sanctions against Iran.
Under the agreement brokered by President Luiz InÃ¡cio Lula da Silva of Brazil and Prime Minister Recep Tayyip Erdogan of Turkey, Iran will ship its low-enriched uranium out of the country in exchange for high-enriched uranium for use at a civilian nuclear research site in Tehran, media reports say.
Iranian authorities hold that the country's activities are for peaceful purposes, while some nations contend they are driven by military ambitions. In 2003 it was discovered that Iran had concealed its nuclear activities for 18 years in breach of its obligations under the Nuclear Non-Proliferation Treaty (NPT).
The UN International Atomic Energy Agency (IAEA) has repeatedly stated that it cannot confirm that all Iran's nuclear material is for peaceful activities because the country has not provided the necessary cooperation.
Mr. Ban, according to his spokesperson, Martin Nesirky, believes that enhanced openness is crucial in alleviating concerns over Iran's nuclear programme, with the new deal possibly helping build confidence about its nuclear activities if also followed by broader engagement with the IAEA and with the international community.
The IAEA has received the text of the Joint Declaration signed yesterday by Iran, Brazil and Turkey, and the Agency is awaiting written notification from Tehran that it agrees with the relevant provisions in the agreement.
The Secretary-General, Mr. Nesirky said, looks forward to the IAEA's assessment on the substantive elements of the Declaration.
"He also urges once again that Iran comply fully with the relevant Security Council resolutions and provide cooperation to the IAEA to the fullest extent to resolve all the outstanding concerns over its nuclear programmes."
This development comes as more than 100 nations are continuing their five-yearly review conference of the NPT to discuss how to further full implementation and enhance the universality of the pact.
On the first day of the gathering, Mr. Ban personally urged Iranian President Mahmoud Ahmadinejad to restore international trust in the peaceful nature of his country's nuclear programme by adhering to the resolutions of the Security Council and the IAEA.
At a meeting requested by Mr. Ahmadinejad, the Secretary-General urged the resumption of talks between Iran and a group of six countries - China, France, Germany, Russia, United Kingdom and United States.
In his opening remarks to the NPT conference, Mr. Ban stressed that it was up to Iran to take the initiative. "Let me be clear: the onus is on Iran to clarify the doubts and concerns of its programme," he said.
In response, Mr. Ahmadinejad told the conference no credible proof had been provided that Iran had anything but peaceful intentions.
The Security Council has imposed several rounds of sanctions on Iran, including a ban on all items which could contribute to the country's enrichment of uranium, a necessary step for both peaceful and militaristic uses of nuclear energy, and arms sales and a freeze on assets.
Last October, a draft agreement on fuel for a civilian nuclear research site in Tehran was put forward in which Iranian low-enriched uranium would be shipped for further enrichment to Russia and then on to France to be fabricated into fuel, but Iran has yet to approve the deal.