TEHRAN (AP) — Iranian scientists have produced their first nuclear fuel rod, Iran’s nuclear agency said Sunday, another step despite United Nations sanctions and measures by the United States and others to stop the nation’s atomic work and shut down any possible pathways to weapons production.

Iran has long said it is forced to seek a way to manufacture the fuel rods on its own, since the sanctions ban it from buying them on foreign markets. Nuclear fuel rods are tubes containing pellets of enriched uranium that provide fuel for reactors.

Iran’s atomic energy agency’s Web site said the domestically made fuel rod had already been inserted into the core of Tehran’s research nuclear reactor, but the claim could not be verified.

The United States and some of its European allies accuse Iran of using its nuclear program as a cover to develop atomic weapons. Iran denies the charge, saying the program is for peaceful purposes only and is geared toward generating electricity and producing medical radioisotopes to treat cancer patients.