Iran significantly reduced its stock of 20 percent-enriched uranium by converting it to reactor fuel, a senior official said, an announcement that appears to be a bid to ease international concerns over its nuclear program.

The West remains concerned over Iran's continuing production of 20 percent uranium, which is enriched to a higher level than that used to fuel most energy reactors and is closer to the 90 percent needed for a warhead. The U.S. and its allies demand Iran halt all enrichment, which Tehran rejects.

The late Thursday announcement, from the government of moderate President Hasan Rouhani, appeared to be a signal to ease Western worries. Speaking to state television, Iran's nuclear chief Ali Akbar Salehi said the country's stocks of 20 percent-enriched uranium has fallen from 240 kilograms to around 140 kilograms as it is converted into fuel for a medical research reactor. Salehi said the remainder is also being converted.

"We have converted a remarkable part to fuel rod," Salehi said. "The amount of 20 percent-enriched uranium is small."

An August report by the United Nations' nuclear watchdog put Iran's stockpile 20 percent enriched uranium at 185.5 kilograms. Some 250 kilograms of the 20 percent enriched uranium is enough for a bomb _ if it is refined more than 90 percent.

The West suspects Iran's nuclear program has military dimension. Iran denies the charge and says its program is for peaceful applications like power generation and cancer treatment.

Salehi's remarks came ahead of a new round of talks planned for later this month between Iran and the U.N. nuclear agency. Talks over the past years failed to reach any breakthrough.

It also came a few days after Rouhani showed a willingness to use his coming visit to the U.N. General Assembly as a point for resuming nuclear talks with world powers.

Earlier Thursday, the new Iranian envoy to the U.N. agency said in Vienna that Tehran was ready for more engagement to clarify its disputed nuclear program. However, Reza Najafi stressed Iran would never give up its "inalienable right to develop a nuclear program," the official IRNA news agency reported Friday.

"Iran is ready to engage and remove any ambiguity," Najafi said, according to the report. He added: "If other sides want a proper response, the West should speak to Iran not with a language of threats or sanctions but with a language of respect."

A disarmament expert, Najafi, 51, replaced former envoy Ali Asghar Soltanieh after Rouhani came to power in August.