The package, presented by European Union Foreign Policy Chief Javier Solana, offers a variety of incentives and fresh multilateral talks if the Islamic republic agrees to suspend uranium enrichment work, which can make both reactor fuel and weapons.

"There are positive steps in the proposal, and there are also

some ambiguities that should be cleared up," Iran's top national security official Ali Larijani said on state television.

"We consider that the Europeans will to solve the issue through talks is a correct step, and we welcome this," he said after receiving the proposal and holding two hours of talks with Solana.

"We had good discussions," Solana said, while asserting that "there is a strong consensus between the six countries" behind the package. The offer has been drawn up by Britain, France and Germany and backed by the United States, Russia and China.

"Now that the proposal is on the table, I hope we will receive a positive response which will be satisfactory to both sides," he said after also meeting Foreign Minister Manouchehr Mottaki and ending his whirlwind visit to Tehran.

Patience needed

Western officials have said Iran -- which has so far refused to

freeze enrichment work -- will be expected to give its response

within a matter of weeks.

A string of tough comments from Iranian officials have left many diplomats fearing that the offer could prove to be dead on arrival -- but Larijani asserted that it would be studied.

"They submitted the proposals and the discussions were good. We have to examine these proposals and then we will give our response," he said.

He did not elaborate on what the "ambiguities" were -- but Iran

will undoubtedly have questions over the scope and duration of a nuclear suspension.

Iranian officials have signaled they may be willing to hold off on industrial-scale enrichment, but they say "research" work cannot be halted.

While being offered carrots, Iran also faces the stick of robust Security Council action -- including a range of possible sanctions -- if it rejects the offer and continues what the West fears is a covert weapons drive.

"I would counsel patience," White House spokesman Tony Snow told reporters in Washington on Monday.

"At this point, as we've said all along, let's give it time. Let's let the Iranians take a look at what the offers are, at the incentives and disincentives."

"There is hope"

Although the United States has not ruled out taking military action, diplomats say it has helped sweeten the package by offering to lift certain sanctions if Iran agrees to an enrichment freeze.

Washington, whose ties with Tehran were severed more than two decades ago, has banned most US trade and investment in the Islamic republic since the mid-1990s.

"The condition for getting to the negotiating table is to suspend enrichment-related and reprocessing activities. That's the first step. Should that happen, then the whole series of other things can take place," Snow said.

"There's neither optimism nor pessimism; there is hope."

Iran maintains defiant stance

On Saturday, Iranian President Mahmoud Ahmadinejad revealed that he had been asked by UN Secretary General Kofi Annan "to examine the proposals and not act hastily."

But the president has consistently ruled out halting enrichment: "They say that they want to give us incentives. They think that they can take away our gold and give us some nuts and chocolate in exchange," he said last month.

Iran's supreme leader Ayatollah Ali Khamenei also vowed Sunday that his country would not buckle in the face of "threats and bribes" and spoke of Iran's "scientific progress" as "representative of our political independence and national self-confidence."