Iran is producing fuel rods for nuclear reactors, state radio reported Thursday in the government's latest attempt to boost a nuclear program that world powers are trying to curb.

Power-control rods, or fuel rods, contain low-enriched uranium and are inserted into a nuclear reactor's core to make the reactor run.

"After sanctions from the U.S., experts from Iran's atomic energy organization have produced better quality rods than the foreign samples," the radio reported.

It said these Iranian-produced rods were already in use in a 5-megawatt reactor built by the United States — before Iran's 1979 Islamic revolution — at the nuclear research center in Tehran.

Enriched uranium can be used in the production of nuclear energy or weapons. Iran, a signatory to the Nuclear Non-Proliferation Treaty, insists its nuclear program is aimed only at producing electricity.

But the United States, France and Britain are pressing for a U.N. Security Council resolution that would demand Iran abandon uranium enrichment or face the threat of unspecified further measures.

Wade Boese, a research director at the Arms Control Association, said that mastering the production of fuel rods was not a major technical development.

"It doesn't strike me as the most significant step forward," Boese said in Washington.

The key notch toward nuclear technology and weapons is the capacity to enrich uranium, which Iran has already announced. Boese said the power-control rod was a purely technical device used in any nuclear reactor.

The new announcement showed Iran was trying to prove its overall intent to produce energy, not warheads, Boese said. "I think they're saying this to bolster their peaceful bona fides," he said.

Iran's top nuclear negotiator Ali Larijani said earlier this week that a first nuclear plant would be fully operational in 2007. Iran had expected the Bushehr plant, which was built with Russian help, to be in operation by the end of this year.