In a major policy shift, the United States offered on Wednesday to join the European governments in direct nuclear talks with Iran if Tehran suspended its uranium enrichment activities, which Western powers believe are aimed at developing an atomic bomb.

"To underscore our commitment to a diplomatic solution and to enhance prospects for success, as soon as Iran fully and verifiably suspends its enrichment and reprocessing activities, the U.S. will come to the table," the U.S. Secretary of State Condoleezza Rice said.

In an initial response from Iran, an Iranian lawmaker dismissed the offer, saying suspension of enrichment was "not on the agenda of the Iranian government" and was an unacceptable condition

The official Iranian news agency IRNA also rejected the U.S. offer as a "propaganda move."

"It's evident that the Islamic Republic of Iran only accepts proposals and conditions that meet the interests of the nation and the country. Halting enrichment definitely does not meet such interests," the IRNA said.

But major European nations, including France, Britain and Germany, which have spearheaded nuclear talks with Iran, hailed the U.S. offer and urged Tehran not to miss the chance to defuse the crisis.

"The U.S. offer will, therefore, give added weight to the proposals which foreign ministers will be discussing in Vienna tomorrow. I urge Iran to respond positively to this opportunity," said Britain's Foreign Secretary Margaret Beckett before meeting her counterparts in Vienna on Thursday.

"(It is) a decisive phase to show Iran an alternative," said Martin Jaeger, chief spokesman for the German Foreign Office.

"We are going into these talks with a certain amount of optimism even though they will not be easy," he said.

Meanwhile, French Foreign Minister Philippe Douste-Blazy also welcomed Washington's latest decision on Iran's nuclear program.

"I welcome the availability of the United States, and possibly of other partners, to join the negotiations launched by Germany, Britain and France with Iran," he said in a statement.

Foreign ministers of five permanent members of the UN Security Council and Germany, as well as the EU foreign policy chief Javier Solana will meet in Vienna on Thursday to finalize a package of incentives to Iran and a UN resolution demanding that Iran end its enrichment activities.

Solana hailed the U.S. offer on Wednesday. "Direct U.S. participation would be the strongest and most positive signal of our common wish to reach an agreement with Iran," Solana said in a statement.

"This important statement by the U.S. administration reinforcesour hope that out of the current discussions, we will be able to establish a new and cooperative relationship with Iran, based on mutual confidence," he said.

During a one-day visit to Finland, Solana said on Wednesday in Helsinki that the EU would make "a generous offer" to Iran.

On the same day, Mohamed ElBaradei, head of the International Atomic Energy Agency (IAEA), also welcomed the U.S. proposal to join the multilateral talks with Iran.

Iran was strongly urged "to create the conditions necessary forthe resumption of these talks, with U.S. participation," ElBaradei said in a statement.

The goal must be to reach a "comprehensive agreement" that was acceptable to both the international community and Iran, ElBaradei said.