Story highlights Iran built its first nuclear fuel rod containing natural uranium, news agency says

The rod is placed in the core of the Tehran research reactor, according to Fars

There are growing fears from the West that Iran is getting closer to building a nuclear weapon

Iran has insisted its nuclear program is for civilian energy purposes only

Iran has succeeded in building and testing the country's first domestically produced nuclear fuel rod, the semi-official Fars news agency reported Sunday.

The uranium fuel rod was tested successfully and installed in the core of a research reactor in Tehran, the news agency said, citing Iran's atomic energy agency website.

Fuel rods are stacks of low-enriched uranium pellets that are bundled together at the core of a nuclear reactor. Sunday's announcement appeared aimed at demonstrating Iran's growing sophistication in developing a home-grown nuclear program, amid fears from the West that it will use its knowledge to build nuclear weapons.

In January 2008, Fars reported that Iran was able to produce everything it needs for the nuclear fuel cycle, making its nuclear program self-sufficient. But it was not clear that Tehran actually had the technology to turn enriched uranium into fuel rods.

Iran has repeatedly insisted its nuclear program is for peaceful, civilian energy purposes only. But it has rebuffed repeated demands to halt its production of enriched uranium, and a November 8 report by the U.N. nuclear watchdog found "credible" information that Tehran has carried out work toward nuclear weapons -- including tests of possible bomb components.

After the report, the governing council of the International Atomic Energy Agency adopted a resolution expressing "deep and increasing concern about the unresolved issues regarding the Iranian nuclear program."

The Islamic republic responded to the IAEA report by calling it a fabrication aimed at bolstering U.S. accusations that Iran is working toward a bomb.

"We will never ever suspend our enrichment," Ali Asghar Soltanieh, Iran's permanent envoy to the IAEA, said in November.

In December, the United States as well as several other Western and Asian nations announced increased sanctions against Iran in an international effort to tighten the screws around the suspected nuclear weapons program.