The IAEA Board of Governors is to debate a European draft resolution calling for Iran to halt its uranium-enrichment program and stop work on a heavy-water reactor that could produce bomb-grade plutonium.

A meeting last week between the IAEA and Iranian officials revealed that Tehran has centrifuge plans, which would be capable of equipping several nuclear warheads a year. Tehran has described the project until now as a small research and development experiment.

The U.S. ambassador to the IAEA in Vienna, Kenneth Brill, says such disclosures show that Iran is continuing to cover up sensitive aspects of its nuclear program.

"Iran is not doing what it should be doing to resolve this issue, and they are not providing the agency with accurate information. They're not providing timely information. They're still trying to hide what they are doing."

The ambassador says there are still many outstanding questions concerning the origins of highly enriched uranium contamination on equipment found at sites in Iran. Diplomats say the IAEA is still investigating Iran's account that the contamination was already on the equipment when it was imported, possibly from Pakistan or Russia.

The country's foreign minister said Saturday Iran will not tolerate further restrictions on its sovereignty and its right to use peaceful nuclear energy. Foreign Minister Kamal Kharazzi said the European draft resolution is unacceptable.

Tehran has indicated that if the IAEA board passes a tough resolution this week, it might not ratify an Additional Protocol allowing for short-notice inspections of its nuclear-related facilities. Iran is not represented on the 35-nation IAEA board, but it usually lobbies for support from the Non-Aligned countries, such as Malaysia and Cuba. But diplomats say, even those countries are becoming frustrated with the lack of progress in dispelling suspicions that Iran could be building nuclear weapons.

Iran has been on the IAEA agenda for more than a year, and has often blocked inspections, making reports by the agency's staff late.

IAEA chief Mohamed ElBaradei, says it is premature to make a judgment on the nature and purpose of Iran's nuclear plans. But Mr. ElBaradei wants changes made to the Nuclear Non-Proliferation Treaty that would make it impossible for states to advance legally along the nuclear fuel cycle, and then switch to a bomb-making program at a later stage.