"We positively evaluate this offer," top Iranian negotiator Ali Larijani was quoted as saying by RIA Novosti news agency after talks with Russian security and energy officials in Moscow.
He added that "this plan can be perfected" during further Russian-Iranian talks planned next month.
Under the proposed deal, uranium for Iran's nascent nuclear power program would be enriched in Russia in order to keep tabs on the material.
This would also allay Western and Israeli fears that Iran secretly plans to build a nuclear weapon under cover of the civilian power project, a development that would upset a longstanding security balance in the Middle East.
The European Union and the United States have given backing to the plan, and British Foreign Secretary Jack Straw said Wednesday that it "may provide a solution" to the impasse.
However, the Iranian negotiator warned any deal would be scuppered if his country's nuclear program was referred for discussion at the UN Security Council, a move that would allow Western powers to press for sanctions against Iran.
"If the matter is referred to the UN Security Council or is used for political pressure, Iran will begin industrial enrichment of uranium," he was quoted as saying by ITAR-TASS news agency.
At the request of Britain, Germany and France, the UN nuclear watchdog International Atomic Energy Agency (IAEA) will hold an emergency meeting in Vienna February 2-3 to discuss the Iranian program. The IAEA could decide to send Iran to the UN Security Council.
Military strike
Security analysts say that the United States has military options to use against Iran even though it is concentrating now on a diplomatic campaign to head off any Iranian move to develop a nuclear bomb.
For most experts a bombing strike against a limited number of suspected nuclear sites is the most likely option being considered.
The GlobalSecurity.org consultancy said there are about two dozen suspected nuclear facilities in Iran and that the Bushehr 1,000 megawatt nuclear plant would be a prime target.
Also the suspected nuclear facilities at Natanz and Arak will likely be targets of an air attack by B-2 or F-117 bombers, it said in an analysis on the crisis.
"American air strikes on Iran would vastly exceed the scope of the 1981 Israeli attack on the Osiraq nuclear center in Iraq, and would more resemble the opening days of the 2003 air campaign against Iraq," GlobalSecurity.org said.
But Peter Brookes, an expert on national security and foreign policy at the Heritage Foundation think-tank, said that "flattening Iran's nuclear infrastructure isn't easy or risk-free" because most of the facilities are underground.
"Iran burrowed many sites deep below the soil, making them much tougher targets (it also put some sites near populated areas to make civilian casualities a certainty if attacked)," he said in a report.
Mr Brookes said there were about 20 known nuclear sites across Iran but the final figure could be higher than 70.
The United States could also carry out a "more comprehensive set of strikes" against nuclear and other military targets "that might be used to counterattack against US forces in Iraq", GlobalSecurity.org said.
Another option would be an invasion, but with US forces already stretched in Iraq such an operation appears unlikely.
Reaction unclear
But US Army Secretary Francis Harvey said last week that the United States could deploy 15 extra brigades, between 45,000 and 75,000 troops, if it faced a new crisis. Iran's reaction to any kind of military action remains unclear.
Joseph Cirincione, director for non-proliferation at the Carnegie Endowment for International Peace, said an attack could "rally the Iranian public around an otherwise unpopular government and jeopardize further the US position in Iraq."
"The strike would not, as is often said, delay the Iranian program. It would almost certainly speed it up," he commented.
Mr Cirincione called the Israeli strike in 1981 "a tactical success but a strategic failure" because it accelerated the Iranian nuclear program.
Brookes also warned of a potentially extreme response by Iran against the United States and Israel.
"The Iranian regime is already up to its neck in the insurgencies in Iraq and Afghanistan. It could certainly increase its financial/material support to the Sunni insurgents, Shia militants, Al-Qaeda and the Taliban to destabilize the new Baghdad and Kabul governments," he said.
"It could also mess with other nations' oil exports, attacking tankers in the Gulf using mines, subs, patrol boats or anti-ship missiles.
"The mullahs could unleash their terrorist attack dogs Hezbollah, Hamas and Palestinian Islamic Jihad against Israel, killing untold numbers in suicide attacks."
The Atlantic Monthly magazine staged a war game simulation of such an attack in 2004 with security experts.
It concluded that the United States had "no way of predicting the long-term strategic impact of such a strike.