Six-nation talks with Iran have ended in failure because no agreement could be reached on the country's nuclear enrichment program, the European Union's foreign policy chief said on Saturday.

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European Union foreign policy chief Catherine Ashton arrives to address the media after two-day talks between Iran and world powers on Iran's nuclear program at the historical Ciragan Palace in Istanbul. ((Burhan Ozbilici/Associated Press))

Catherine Ashton said no new date for another meeting had been set.

She said the talks in Istanbul foundered on Iran's insistence that the UN Security Council lift sanctions imposed because of Iran's refusal to stop uranium enrichment as a precondition for new negotiations.

Iran was also seeking recognition by the six powers that Iran had a right to enrich.

Proposals by the six for improved UN monitoring of Iran's nuclear activities were rejected by Tehran, as were attempts to kick-start dialogue through reviving a subset of international talks focusing on Iran shipping out a limited amount of its enriched uranium in exchange for fuel for its research reactor, Ashton said.

"We had hoped to have a detailed and constructive discussion of those ideas," she said. "But it became clear that the Iranian side was not ready for this unless we agree to preconditions related to enrichment and sanctions.

"Both these preconditions are not the way to proceed," she told reporters.

While no new talks were planned, Ashton said, "our proposals remain on the table.

"Our door remains open. Our telephone lines remain open.

"The process can go forward if Iran chooses to respond positively," she said. "We will now wait to see whether they do."

China, Britain, France, Russia, the United States, and Germany hope to nudge Iran toward acknowledging the need to reduce worries that it might turn its enrichment program to making weapons.

Tehran denies that it wants nuclear arms, insisting it wants only to make peaceful nuclear energy for its increasing population. But concerns have grown — because its uranium enrichment program could also make fissile warhead material, because of its nuclear secrecy and also because the Islamic Republic refuses to co-operate with UN attempts to investigate suspicions that it ran experiments related to making nuclear weapons.

Iran turns focus away from nuclear program

While the six went into the first day of talks Friday formally focused on freezing Iran's uranium enrichment program, Tehran has repeatedly said this activity is not up for discussion. Instead, Iranian officials came to the table with an agenda that covered just about everything except its nuclear program: global disarmament, Israel's suspected nuclear arsenal, and Tehran's concerns about U.S. military bases in Iraq and elsewhere.

As talks resumed Saturday, Iranian delegate Abolfazl Zohrevand said the atmosphere was "positive."

"Both sides showed the willingness that a solution can be achieved to reach active co-operation on various issues," he told AP Television News.

But diplomats from two other delegations familiar with the negotiations were less bullish, with one suggesting shortly before the end of the meeting that the talks were in trouble because Iran was sticking to its demands on the lifting of sanctions and acceptance of Iran's enrichment activities.