Tehran, Iran ? Iran said Sunday that within days it would resume building centrifuges for its nuclear program in a forceful rejection of severe international castigation.

But Tehran said it welcomed international supervision of the building program and said it would not use the devices to enrich uranium — for the time being. The process can make uranium into fuel for peaceful or military nuclear purposes.

The White House called Iran’s decision further proof it was trying to build an atomic bomb, and the head of the International Atomic Energy Agency — the U.N.’s nuclear watchdog — said in Moscow that he hoped Iran would reverse its decision.

“Iran’s continued failure to comply with the IAEA and continued failure to (halt) all enrichment-related reprocessing activities only reinforces the concerns we have expressed,” White House spokesman Scott McClellan said in Washington. “Iran needs to come clean and fully cooperate with its international obligations.”

Iran suspended the building of centrifuges and the enrichment of uranium under international pressure, part of the IAEA’s attempts to determine the intent of Iran’s nuclear program, much of which was kept secret for years.

The United States accuses Iran of trying to build nuclear weapons, and President Bush has labeled Iran part of an “axis of evil” with North Korea and prewar Iraq.