The European Union hailed the Unites States' conditional offer to join direct talks on Iran's nuclear program, saying it strengthens their hand in negotiations with Tehran.

French Foreign Minister Philippe Douste-Blazy, who along with his British and German counterparts has spearheaded diplomatic efforts to engage Tehran, said the US policy shift "reinforces the credibility" of Europe's efforts.

In Berlin, Foreign Minister Frank-Walter Steinmeier said ahead of the Vienna talks Thursday that Washington's offer was "a real strengthening of American efforts."

"I see a window opening" which could bring about a solution, Steinmeier said, flanked by his Dutch counterpart Ben Bot. Both ministers said they hoped Iran would understand the significance of the offer and seize the opportunity.

First US direct talks with Iran in decades

The US offer came on the eve of a meeting in the Austrian capital of the five permanent members of the UN Security Council -- the United States, Russia, France, Britain and China -- plus Germany.

Specifically, US Secretary of State Condoleezza Rice said Washington is ready to join direct talks with Europe on Iran's nuclear program if Tehran suspends all uranium enrichment activities.

She made the offer of the first substantive talks with Iran since diplomatic ties were broken off 26 years ago as she prepared to leave for the crucial meeting of world powers in Vienna on Tehran's suspected nuclear arms program.

"To underscore our commitment to a diplomatic solution and to enhance the prospects for success, as soon as Iran fully and verifiably suspends its enrichment and reprocessing activities, the United States will come to the table with our EU-3 colleagues and meet with Iran's representatives," she said.

EU foreign policy chief Javier Solana said US participation "would be the strongest and most positive signal of our common wish to reach an agreement with Iran."

"This important statement by the US administration reinforces our 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.

Chance of tack

One EU diplomat said the US change of tack could be decisive.

"When you add the US to direct negotiations, a country which has not had direct relations with Iran since the arrival of Khomeini ... the value of the negotiations changes substantially," he said. "It is a very important signal of the commitment of the US and their desire to see the negotiations succeed."

Washington heavily backed the former Iranian imperial regime of the Shah, which was toppled in 1979 and replaced by an Islamic republic headed by Ayatollah Ruhollah Khomeini.

Russian Foreign Minister Sergey Lavrov, visiting Turkey Wednesday, said, "We hope the way will be open to a political solution after the talks in Vienna."

Iranian reluctancce

But Iran on Thursday rejected US conditions for talks, saying it was ready for negotiations but unwilling to freeze sensitive nuclear work.

"We support dialogue in a fair and unbiased atmosphere, but we will not talk about our undeniable and legitimate rights, because this is the right of our people according to international laws and treaties," Foreign Minister Manouchehr Mottaki told reporters. "We are ready to talk about common concerns and if the conditions are such in a way that we have outlined ... we are ready to negotiate with all parties."

Mottaki said that Rice's statement -- which also touched on US concerns over Iran's human rights record and its alleged support for terrorism -- "did not have any new words in it."

"They have repeated their old words. A new solution and a logical solution for the nuclear issue was not seen in the declaration," said Mottaki, giving the Islamic republic's first reaction to the US proposal. "Maybe they wanted to cover up their crimes in the region. First and foremost, the US should be held accountable for their crimes in Iraq, Afghanistan, the prisons of Guantanamo and (Baghdad's) Abu Ghraib (jail)."