The Western nations want to invoke Chapter 7 of the U.N. Charter that would allow economic sanctions or military action, if necessary, to force Iran's compliance. Russia and China, the other two permanent Security Council members ¡ª all of whom have veto power ¡ª oppose such moves.

The U.S. ambassador to the United Nations, John Bolton, said Sunday he believed the resolution would move to a vote this week, with or without support from Moscow and Beijing. He dismissed the Iranian parliament's threat, saying it would not deter a U.N. resolution.

"It shows they remain desperate to conceal that their nuclear program is in fact a weapons program," he said.

Sen. John McCain (news, bio, voting record), R-Ariz., said Sunday that Washington should consider direct nuclear talks with Iran, but added that "there has to be some kind of glimmer of hope or optimism before we sit down and give them that kind of legitimacy."

McCain, a possible presidential contender in 2008, told CBS' Face the Nation that Iran must renounce its call for the extinction of direct talks, McCain said, are "a tough decision, because here's a country whose rhetoric daily continues to be the most insulting to the United States and to democracy and freedom."

But, he said, "it's an option that you probably have to consider."

North Korea agreed last September to give up its nuclear program in exchange for U.S. aid and security assurances, but negotiations have been stalled since November, mainly because of Pyongyang's anger over U.S. sanctions for alleged currency counterfeiting and money laundering.

North Korea escaped punishment by the U.N. Security Council, but Iran's possible departure from the treaty is likely to bring a tougher response.

Ahmadinejad restated his readiness to jettison treaty membership.

"If a signature on an international treaty causes the rights of a nation be violated, that nation will reconsider its decision and that treaty will be invalid," he told the state news agency.

He called threats of sanctions "meaningless" and vowed to "smash their (U.S.-backed) illegitimate resolutions against a wall."

Foreign Ministry spokesman Hamid Reza Asefi said any U.N. resolution would be "completely illegal" and driven by politics.

"It's clear that any action by the U.N. Security Council will leave a negative impact on our cooperation with the IAEA," he said, adding that such action would "change the path of cooperation to confrontation."

The IAEA declared in 2002 that Iran had been conducting secret nuclear activities for decades, though it has never said Tehran has a weapons program.

Iran claims it has that right, including the privilege of enriching uranium, under its treaty membership, but its opponents claim it ceded that right by hiding parts of its nuclear program from the international community.

In February, Iran barred intrusive inspections of its nuclear facilities by the IAEA after it was referred to the Security Council. Iran said it had been implementing the agreement since 2003 voluntarily but it had not won domestic approval, as necessary, from parliament and the Guardian Council, a powerful oversight body dominated by Islamic hard-liners.

Iran declared yet again Sunday it would not give up uranium enrichment despite the building crisis.

"We won't give up our rights and the issue of suspension (of enrichment) is not on our agenda," Asefi said at his weekly briefing.