Mohamed ElBaradei, Director General of the International Atomic Energy Agency, IAEA (l) shakes hands with Brazil's Foreign Minister Celso Amorim, during a meeting in Brasilia, Brazil, 05 Dec 2007

The head of the International Atomic Energy Agency says a new U.S. intelligence report offers Iran a "window of opportunity" to prove that its nuclear program is for peaceful purposes.

Mohamed ElBaradei said Wednesday during a visit to Brazil that the U.S. report is consistent with the U.N. nuclear agency's assessment of Iran's atomic program.

The U.S. National Intelligence Estimate released this week says Iran halted a secret nuclear weapons program four years ago - contradicting the Bush administration's charge that Tehran is actively seeking nuclear weapons.

Iranian President Mahmoud Ahmadinejad said Wednesday the U.S. report is "a victory" for the Iranian nation against world powers. He also said Iran will not retreat "one step" in its pursuit of peaceful nuclear technology.

However, U.S. Secretary of State Condoleezza Rice said Wednesday Washington will continue pushing for a third U.N. sanctions resolution against Iran to help prevent it from acquiring uranium enrichment technology.

The report also said Iran likely would be capable of producing enough enriched uranium for a nuclear weapon between 2010 and 2015.

Enriching uranium is a key process to develop fuel for atomic weapons.

Commenting on the U.S. assessment, Russian Foreign Minister Sergei Lavrov said his government has seen no evidence that Iran ever had a nuclear weapons program.

Some information for this report was provided by AFP, AP and Reuters.