The head of the U.S. mission to the IAEA, Ambassador Kenneth Brill, told reporters Iran has engaged in what he called a continuing pattern of deception and delayed admissions about its nuclear activities.

Ambassador Brill said Iran's actions, as well as information in an IAEA report report made public on Tuesday, strengthen the U.S. assessment that, in his words, Iran's nuclear program is not consistent with its stated purpose, but is clearly geared towards the development of nuclear weapons.

Iran gave the IAEA what it claims was a full and accurate report on its nuclear program last October. Since then international inspectors have worked at nuclear facilities in Iran, and their findings are in the report leaked on Tuesday. The report will be presented to IAEA's board of governors in March.

IAEA spokeswoman Melissa Fleming said some progress has been made with Iran, but there are still some concerns. "With regard to the IAEA's ability to access sites, we have seen some good co-operation from Iran. However, the IAEA would like to see much more prompt information. One setback is the disclosure of the P-2 centrifuge designs that was not declared by Iran," she said.

These advanced centrifuges can speed up the process for making a nuclear bomb, but they can also be used in a civilian program, which is what Iran claims.

Iran says it is not required to disclose all information to the IAEA because an agreement called the Additional Protocol is not yet in force. Iran signed the protocol to the Nuclear Non-Proliferation Treaty last year and would give the IAEA greater rights to information. The protocol must be ratified by the Iranian parliament before it can go into effect. But Iran has allowed the inspectors some additional access in recent months anyway. The IAEA says Iran must provide all information on its nuclear program and clarify the inconsistencies and discrepancies in what it has submitted so far.