The fuel -- whose source country has not been specified -- could be used in the commercial reactor that Russia is building under contract for Tehran near Iran's Gulf port of Bushehr or in other reactors that Tehran wants to build in the future.
In exchange, the three European states are asking Tehran to commit to what amounts to a permanent suspension of its efforts to master the process of enriching uranium. That process includes mining uranium ore, converting it to a gaseous form, and enriching the gas into a fissile fuel. Iran's efforts to master the process worry many Western states because uranium enriched to low-levels can be used as reactor fuel but highly enriched uranium can be used to make nuclear bombs.
Shannon Kile, a nuclear expert at the Stockholm International Peace Research Institute in Sweden, says the three European states are also offering Iran trade incentives to sweeten the deal.
"And, of course, there are other inducements as well, opening negotiations on the trade and cooperation agreement, which is something they are holding out a little bit further down the line, improving political ties, [and] cooperation on other regional security issues, for example, interdicting drug trafficking and organized crime," Kile said.
The three European powers are also reported to be asking Iran to give up separate efforts to build a "heavy-water" nuclear reactor which produces plutonium -- a highly fissile material that is useable in medical research but is also a base for making nuclear bombs.
As incentive, the Europeans are believed to be ready to offer their support for Iran's building of "light-water" reactors like the one under construction at Bushehr. The by-products of light-water reactors are less easily convertible to bomb-making materials than are the by-products of heavy-water reactors.
In the run-up to today's meeting at the Vienna-based International Atomic Energy Agency (IAEA), Tehran has given no signs that it will accept the Europeans' terms.
Iranian President Hojatoleslam Mohammad Khatami said yesterday that Iran reserves the right to develop all aspects of nuclear technology connected to a peaceful energy program.
"I still do not know what the European proposal is, but we have always stated that we are ready for negotiations and talks. We are also ready to reach understanding. We expect recognition of our unquestionable right, and not being deprived of having [access to] peaceful nuclear technology under the IAEA's full supervision," Khatami said.
This week's proposal is the latest major initiative by Britain, France, and Germany to try to end the long-standing crisis over Iran's nuclear program.
That crisis has grown as nearly two years of IAEA inspections in Iran have revealed Tehran sought to conceal aspects of its nuclear program for over two decades. Washington has accused Iran of maintaining a covert nuclear weapons development program under the guise of a commercial nuclear program.
The foreign ministers of Britain, France, and Germany flew to Tehran late last year to strike a deal under which Iran agreed to indefinitely suspend activities connected with uranium enrichment in exchange for promises of technical assistance with its commercial program.
However, Iran early this year accused the three states of siding with Washington in backing an IAEA resolution "deploring" Iran's lack of cooperation with UN nuclear inspectors. Tehran has subsequently said it is producing large amounts of gaseous uranium, which is used in enrichment. It has also said it is resuming manufacture of components for high-speed centrifuges which can transform the gas into enriched uranium.
Washington says it is watching the new European effort with interest but has stopped short of endorsing the offer. Representatives of the three EU states met in Washington with top U.S. officials last week to brief them on the plan.
Yesterday, U.S. State Department spokesman Richard Boucher said only that Washington continues to have deep concerns over Iran's nuclear activities.
"We have long had concerns about Iran's acquisition of nuclear capability, of nuclear technology, because for many years we have seen a confirmed pattern of noncompliance with safeguards; we have seen the use of nuclear exchanges, nuclear technology, in order to develop what we can only describe is a nuclear weapons program," Boucher said.
Many analysts say the European offer could be the last attempt by the three key EU states to defuse the crisis before it reaches a showdown at the IAEA.
The U.S. has threatened to ask the IAEA to refer the crisis to the UN Security Council to consider possible punitive actions against Iran, including sanctions. Should Tehran reject the European offer, the three EU states could now lend their support to the U.S. position.
But whether the full IAEA Board of Governors would endorse any U.S. resolution to refer the crisis to the Security Council remains uncertain.
Analyst Kile notes that there are 35 members states on the board of governors. He says some would likely be reluctant to set any precedents for limiting states' abilities to develop a full nuclear fuel cycle if they wish to. Under international nuclear treaties, states have the legal right to develop commercial nuclear industries and many countries have done so.
"There are 35 members states on the IAEA board of governors, and some of those states are countries like Sweden, South Africa, like Brazil, which has an extensive civilian nuclear energy program, and clearly they don't want to see any sort of precedent being set that will give the big powers the right to curtail legitimate civilian nuclear power industrial uses," Kile said.
Russia has not commented directly on the European offer. Moscow is currently negotiating a contract with Tehran to sell it fuel for the Bushehr reactor and require Iran to return spent fuel to Russia.
The IAEA is due to take up the Iran issue again when the board of governors meets on 25 November.