The UN's atomic watchdog says Iran has agreed to consider a deal on its nuclear programme, which could see it ship out most of its enriched uranium to Russia.
If it goes ahead the deal would strip Iran of most of the material it would need to build a nuclear weapon, diplomats said on Wednesday, a move that would help to allay Western fears over Tehran's nuclear ambitions.
Mohamed ElBaradei, director-general of the International Atomic Energy Agency (IAEA), said the draft was drawn up by the US, Russia, France and Iran at a closed conference at the agency's headquarters in Vienna, Austria.
He said the text had been sent to the nations' capitals for approval by Friday.
"I have circulated a draft agreement that reflects, in my judgment, a balanced approach on how to move forward," ElBaradei said.
"If this arrangement holds, I think it will show that Obama's position of sitting down and talking with the Iranians is bearing some fruit. By refusing to sit down with the Iranians, we would not have got as far as this"
Joseph Nye, a foreign policy scholar and former US Assistant Secretary of Defense for International Security Affairs
"Everyone in these talks was trying to look to the future, not the past, and heal the wounds existing for many years ...This [deal, if formally approved], should open space for negotiations."
Neave Barker, Al Jazeera's correspondent in Moscow, said: "There's likely, very much, to be an overwhelming show of support here in Moscow for a plan that is nothing new in terms of Russian diplomacy.
"It dates at least to about four or five years ago when Russia first aired the suggestion that it could be a middle man between the US and Iran over its controversial nuclear programme.
"I think this is very much a gesture of goodwill from the Russian side to the Americans, ever since the [US president Barack] Obama administration came into power there have been exchanges of positive words.
"There was an indication from the Russian military earlier on today that they may well U-turn on an earlier decision to sell S-300 air defence missiles to Iran, an indication that Moscow is perhaps having a rethink over its future ties with Iran".
Ali Asghar Soltanieh, Iran's ambassador to the IAEA, said he welcomed the development.
"We are fully co-operating. We came to this meeting with a spirit of co-operation and flexibility," he said.
Nazanine Moshiri, Al Jazeera's correspondent in Tehran, the Iranian capital, said the final decision over the deal "will be made here in Tehran. And Tehran has said it will not give up its right to develop uranium."
"Just before news of this deal came out, the deputy head of Iran's atomic agency came out with his own statement saying Iran had 'good news' about its nuclear programme, which it will reveal in the next few months.
"We don't know what that good news is but, whatever it is, I'm sure the West will not be pleased about it."
Diplomats told the Reuters news agency that ElBaradei's draft contained the powers' call for Iran to send about 75 per cent of its enriched uranium reserve abroad before the end of this year.
The reserve would be converted into fuel for a Tehran reactor producing medical isotopes.
Russia, France and the US have been pushing Iran to agree to ship 1,200kg of its own stockpiled uranium to Russia, and subsequently France, but ElBaradei did not reveal whether Iran had agreed to that key point.
Despite concern by Western powers that Iran intends to build a nuclear weapon, Tehran has maintained that its programme is aimed at peaceful purposes only.
|Iran has insisted that its nuclear programme
is geared towards peaceful means [EPA]
Hillary Clinton, the US secretary of state, said that if the Iranian government was open to the world on its nuclear file, it could lead to talks on a range of divisive issues between Washington and Tehran.
"If Iran is serious about taking practical steps to address the international community's deep concerns about its nuclear programme, we will continue to engage, both multilaterally and bilaterally, to discuss the full range of issues that have divided Iran and the United States for too long," Clinton said in Washigton on Wednesday.
"The door is open to a better future for Iran, but the process of engagement cannot be open-ended. We are not prepared to talk just for the sake of talking."
Joseph Nye, a foreign policy scholar and former US Assistant Secretary of Defense for International Security Affairs, said that while the offer for Russia to enrich Iran's uranium was a positive step, but said that it did not necessarily constitute "the end of the problem".
"If the Iranians enrich with their existing facilities for a year, they will replace what they will be sending out of the country. In addition, there is still the open question of whether there are secret facilities, where Iran could be enriching, that we do not know about," he told Al Jazeera.
"If this arrangement holds, I think it will show that Obama's position of sitting down and talking with the Iranians is bearing some fruit. By refusing to sit down with the Iranians, we would not have got as far as this."