Tehran, Iran ? Iran told the U.N. nuclear watchdog agency Tuesday it planned to resume nuclear fuel research after a 2 1/2-year hiatus, issuing a fresh challenge to Western nations concerned that Tehran is trying to build an atomic weapon.

International Atomic Energy Agency head Mohamed Elbaradei said it was important that Tehran “maintains its suspension of all enrichment-related activity” as a way of reducing international suspicions about its nuclear plans.

Mohammad Saeedi, deputy head of the Atomic Energy Organization of Iran, said research would “resume in cooperation and coordination with the IAEA in the next few days,” adding that it would “have little to do with the production of nuclear fuel.”

Beyond that, he would not specify what type of research Tehran planned but claimed its nuclear program had suffered significantly during the research suspension. He said Iran could no longer keep its research scientists in limbo.

Iran has said it remains determined, at some point, to resume uranium enrichment, a process that can produce fuel for nuclear weapons.

Hard-line President Mahmoud Ahmadinejad, meanwhile, told lawmakers Tuesday that he had abandoned a previous policy of trying to mollify the West because it had proved fruitless, the official Islamic Republic News Agency reported.

The Tuesday announcement, while vague, was certain to raise further concerns in the United States and among its European allies who believe Iran wants to build a nuclear arsenal. Tehran says its nuclear program is for electricity generation.