Iran is moving to eliminate more of the uranium it could most easily refine into nuclear-bomb material, the U.N. nuclear watchdog said on Friday.

Inspectors last week confirmed that Iran had fed nearly 670 pounds of its 20 percent-enriched uranium-hexafluoride gas into a system at its Isfahan facility for producing solid oxide, the International Atomic Energy Agency said in quarterly safeguards report. The action was in line with a short-term deal the Persian Gulf power reached other governments over fears that it was pursuing an ability to build nuclear bombs.

The country has long insisted its nuclear program is peaceful, but last year agreed to make the 20 percent-enriched uranium harder to use in nuclear weapons. It has already completed plans to blend down half of the stockpile and, on Friday, agency inspectors said efforts to convert the other half into oxide were "ongoing."

Addressing concerns that Iran may be able to return the oxide to its gaseous form, IAEA officials noted that the conversion system at Isfahan contained "no process line ... for the reconversion of uranium oxides into [uranium hexafluoride]."

Iran is pursuing negotiations with six other countries -- China, France, Germany, Russia, the United Kingdom and the United States -- on a potential long-term replacement for the interim nuclear accord reached last November. The temporary arrangement is due to expire on July 20.