Updated

Key European nations are tentatively considering offering Iran a light-water nuclear reactor if as part of incentives meant to persuade Tehran to give up its uranium enrichment program, diplomats and officials said Tuesday.

A U.S. official said Washington would likely oppose the plan.

A senior diplomat familiar with international attempts to dissuade Iran from enrichment said the plans were tentative and still being discussed among France, Britain and Germany as part of a possible package to be presented Friday to senior representatives of the five permanent U.N. Security Council member nations.

He demanded anonymity in exchange for divulging the confidential information.

CountryWatch: Iran

In the British capital, officials confirmed the offer was among options to be discussed at the London talks but said suggestions that it had been decided on as part of the incentives were premature.

"Clearly we are working out the details and that will be a matter for the talks in London," a British foreign office spokesman said on condition of anonymity, in line with government policy.

A French official was more cautious, suggesting all depended on Iran's readiness to discuss details in new negotiations between the Europeans and Tehran.

"We are not going to offer them a finished reactor," he told the AP.

"For the moment, one can only identify large general categories (of cooperation) and only if they say that they are interested ... can we start to discuss the details with them," he said. "Otherwise, we are putting the cart before the horse."

A light-water reactor is considered less likely to be misused for nuclear proliferation than the heavy water facility Iran is currently building at the central city of Arak, which — once completed — will produce plutonium waste.

Still, light water reactors are also not proliferation proof because they use enriched uranium as fuel. While uranium enriched to low levels cannot be used in a weapons programs, it can be processed relatively easily to high "weapons-grade" material, found in the fissile core of nuclear warheads.

Iran recently managed to produce what it says is its first batch of low-enriched uranium. Concerns were heightened last week by revelations that inspectors of the International Atomic Energy Agency had found traces of uranium enriched to levels higher than used for fuel — though not yet weapons grade — at a former research facility linked to the Iranian military.

Fears that Iran's enrichment program could be misused for weapons are at the center of international attempts to strip Tehran of ambitions to enrich domestically. Any European offer of one or more light-water reactors — however far down the road — would have to be conditional on Iran rejecting its enrichment plans and accepting foreign deliveries of low-enriched uranium for fuel. That is something Tehran has hitherto steadfastly rejected.

Washington has been at the forefront of moves to pressure Iran to give up domestic enrichment and has in recent months swung behind a proposal from Moscow to provide Tehran with fuel-grade uranium produced in Russia instead.

An official in an EU capital said the idea had not yet been discussed with the Russians, Chinese and Americans, who — along with France and Britain — are the Security Council's permanent members.

In an initial reaction, a U.S. official told The Associated Press that any plan to offer the Iranians a light-water reactor "would be met with a real sense of skepticism" by the Americans. Even in the unlikely event that the Iranians gave up plans of domestic enrichment in return, such a facility could help them acquire the technology to develop a full-fledged nuclear program with the potential for misuse, he said.

"If Iran is bent on having a nuclear weapons program, we ought not to be helping with that," said the official, echoing U.S. assertions that Iran's activities were a cover for developing the atomic bomb.

In a sign of persisting differences with the United States, Russia's foreign minister said Beijing and Moscow will not vote for the use of force in resolving the nuclear dispute.

After two days of talks with his Chinese counterpart, Russian Foreign Minister Sergey Lavrov said Moscow and Beijing hold identical positions on the nuclear programs by Iran and North Korea: Both disputes require diplomacy, not force.

In an outreach to Tehran, Lavrov also said that Iranian President Mahmoud Ahmadinejad will attend a summit meeting next month in Shanghai of leaders from Russia, China and four Central Asian nations.

"We cannot isolate Iran or exert pressure on it. Far from resolving this issue of proliferation, it will make it more urgent," Lavrov told reporters. "Russia and China will not vote for the use of force in resolving this issue."

Chinese Foreign Ministry spokesman Liu Jianchao, at a separate briefing, also urged more energetic efforts to restart negotiations. "We believe that at the current stage relevant parties should make active gestures to launch a new round of diplomacy," Liu said.