TEHRAN - Iran said on Monday it would welcome constructive dialogue with six world powers, including the United States, in its clearest signal yet it will accept an invitation for talks on its disputed nuclear work.

State television quoted Iran's chief nuclear negotiator Saeed Jalili as making the comment in a telephone conversation with European Union foreign policy chief Javier Solana.

The United States, Russia, China, France, Germany and Britain said on Wednesday they would ask Solana to invite Iran to a meeting to find a diplomatic solution to this critical issue, referring to the long-running nuclear row.

That marked a major shift in U.S. policy under new President Barack Obama, whose predecessor George W. Bush's administration shunned direct talks with Tehran as long as it pressed ahead with nuclear activity the West fears has military aims.

The television report said Solana called for renewed discussions between the two sides aimed at a new era of cooperation. It did not say when he spoke with Jalili.

Jalili welcomed dialogue between Iran and the six countries on constructive cooperation, the television report said.

He emphasized the necessity of correct understanding of international realities and developments.

Jalili said Iran would give an official response to the six powers' statement, issued after a meeting of their senior officials in London last week, without saying when.

IRAN DEFIES PRESSURE

The Obama administration has offered a new beginning of diplomatic engagement if Iran unclenches its fist.

Iranian President Mahmoud Ahmadinejad said on Thursday the Islamic Republic would be ready for talks with the West if they were based on respect and justice.

But Tehran also says it wants to see a real shift in U.S. policy from the Bush administration, which spearheaded a drive to isolate Tehran over its refusal to stop enriching uranium, which can have both civilian and military uses.

Iran, the world's fourth-largest oil producer, says its nuclear program is aimed at generating electricity. It has repeatedly ruled out halting its enrichment program.

We speak very respectfully of Barack Obama. But we are realists. We want to see real changes, Ahmadinejad told German news magazine Der Spiegel in an interview published last week.

Despite reaching out to Tehran, analysts and diplomats say the Obama administration is realistic about its chances of a breakthrough and aware that Iran may use talks to buy time to complete its nuclear program.

While trying to engage Iran, Washington has also warned of tougher sanctions if it continues to defy United Nations demands to halt sensitive nuclear work.

In the Spiegel interview, Ahmadinejad expressed openness for talks with the United States but again dismissed demands on Iran to suspend enrichment: These discussions are old. The time for this is over, he said.

Underlining Iran's determination to continue with its nuclear drive despite Western pressure, Ahmadinejad on April 9 inaugurated its first nuclear fuel fabrication plant and said the country had mastered the entire fuel cycle.