A new U.S. intelligence review that concludes Iran stopped developing a nuclear weapons program in 2003 is consistent with the U.N. atomic watchdog agency's own findings and "should help to defuse the current crisis," the organization's chief said Tuesday.

"Although Iran still needs to clarify some important aspects of its past and present nuclear activities, the agency has no concrete evidence of an ongoing nuclear weapons program or undeclared nuclear facilities in Iran," International Atomic Energy Agency director-general Mohamed ElBaradei said in a statement.

ElBaradei said he viewed "with great interest" Monday's release of a U.S. National Intelligence Estimate that said Tehran halted nuclear weapons development in late 2003 under international pressure.

The chief U.S. envoy to the IAEA, Gregory L. Schulte, said the U.S. assessment contained "some positive news" and raised hopes of a peaceful and diplomatic end to the standoff.

"It does make us more hopeful that diplomacy can succeed, but for diplomacy to succeed, we still need to keep the pressure on while giving Iran a negotiated way out," Schulte told reporters in Vienna.

But "Iran's nuclear file is not closed," he said, adding that the U.S. report "shows we were right to be concerned."

The U.S. report noted that Iran continues to enrich uranium, and senior officials in Washington said that means it still may be able to develop a weapon between 2010 and 2015.

Monday's finding was a shift from two years ago, when U.S. intelligence agencies said they believed Tehran was determined to develop a nuclear capability and was continuing its weapons development program. It suggests that Iran is susceptible to diplomatic pressure, the officials said.

ElBaradei, who was traveling in South America on Tuesday, said the new assessment "should help to defuse the current crisis" over Iran's suspect nuclear program and growing fears that Washington may be gearing up for a possible conflict with the Islamic Republic.

"At the same time, it should prompt Iran to work actively with the IAEA to clarify specific aspects of its past and present nuclear program," he said. "This would allow the agency to provide the required assurances regarding the nature of the program."

In his statement, ElBaradei called on Iran to "accelerate" its cooperation with the IAEA and for all parties "to enter without delay into negotiations."

"Such negotiations are needed to build confidence about the future direction of Iran's nuclear program — concern about which has been repeatedly expressed by the Security Council," he said.

"They are also needed to bring about a comprehensive and durable solution that would normalize the relationship between Iran and the international community," ElBaradei said.