A U.N. nuclear agency report said Iran produced small amounts of plutonium as part of covert nuclear activities. While finding "no evidence" that Tehran tried to make atomic arms, it said such efforts cannot be ruled out.

The significance of the plutonium extraction was unclear. The report by the International Atomic Energy Agency (search) did not link it to weapons activity but it criticized Iran for not reporting its processing activities, listing it among dozens of cases where Tehran had covert programs in place.

"Neither the (processing) activities nor the separated plutonium had been previously reported to the agency," said the report, which was obtained by The Associated Press.

Plutonium (search) can be used in nuclear weapons but it also has uses in peaceful programs to generate power — which is what Iran says is the sole purpose of its nuclear activities.

Meanwhile, a top Iranian official announced in Moscow that his country has suspended its enrichment of uranium and agreed to additional U.N. inspections of its nuclear facilities.

The 29-page report, prepared for a Nov. 20 meeting of the IAEA board of governors, praised Iran's recent cooperation with the agency but also faulted the country for past concealment of its nuclear programs.

The United States accuses Iran of pursuing nuclear weapons and has pressed for the IAEA to declare Tehran in violation of the Nuclear Nonproliferation Treaty — a move that would lead to U.N. Security Council involvement and possible sanctions.

The report credited Iran for a change of heart since September, when the agency demanded it explain contradictions and ambiguities in its nuclear activities.

"To date, there is no evidence that the previously undeclared nuclear material and activities ... were related to a nuclear weapons program," said the report, drawn up by IAEA Director General Mohamed ElBaradei (search).

"However, given Iran's previous pattern of concealment, it will take some time before the agency is able to conclude that Iran's nuclear program is exclusively for peaceful purposes," it added.

U.S. officials will likely seize on a passage in the report saying that Tehran's recent disclosures "clearly show that in the past, Iran had concealed many aspects of its nuclear activities, which resulted in breaches of its obligations of the safeguard agreement."

The safeguards, which are meant to ensure all nuclear activities are peaceful, are a key part of the nonproliferation treaty.

Under international pressure, Iran recently gave the agency what it said was a complete declaration of its nuclear activities just days ahead of an Oct. 31 deadline. On Monday, it also handed over two letters pledging to sign an additional agreement throwing open its program to inspection on demand by agency experts and announcing it had suspended uranium enrichment.

The concessions were announced in Moscow by Hasan Rowhani, the head of Iran's powerful Supreme National Security Council.

"Atomic weapons are not important to our defense doctrine," Rowhani said before meeting Russian President Vladimir Putin, whose government helped build Tehran's nuclear program.

Washington has urged Moscow to freeze an $800 million deal to help build Iran's first nuclear reactor, saying the facility in Bushehr on the shore of the Persian Gulf could help Iran develop weapons. The Kremlin has said it shares some of the U.S. concerns and has prodded Tehran to accept tighter IAEA controls.

Tehran promised weeks ago to suspend its enrichment activities, a key concern, but the timeframe was unclear.

Iran has affirmed that it enriched uranium covertly at a sophisticated facility at Natanz, about 300 miles south of Tehran. But it maintains enrichment was only to non-weapons levels, as part of nuclear programs to generate electricity.

Traces of weapons-grade uranium have been found on enrichment centrifuges at two Iranian facilities, but Iranian officials say the imported equipment was contaminated abroad before Iran received it.

"Iran has now acknowledged that it has been developing, for 18 years, a uranium centrifuge program, and, for 12 years, a laser enrichment program," the report said.

U.S. intelligence reports focus on the Natanz enrichment programs in arguing that Iran has been pursuing a clandestine nuclear weapons program.

The ElBaradei report did not make a judgment on the source of the highly enriched uranium, saying more investigation was needed.

The report also welcomed Iran's "active cooperation and openness" implemented since the last IAEA board meeting.

Before that, however, Iran "failed in a number of instances over an extended period of time to meet its obligations" on honoring its safeguards agreements, said the report. "Iran's policy of concealment continued until last month, with cooperation being limited and reactive and information being slow in coming."

By making his announcement in Moscow, Rowhani bolstered the prestige of the Kremlin, which had taken a position between Washington and Tehran in the dispute.

Putin said "we are pleased to note that Iran has itself resolved to limit itself" on uranium enrichment, and he suggested it cleared the way for further Russian-Iranian nuclear cooperation.

Rowhani added that Iran already had a project in mind.