The surprise comments by Iran's top nuclear negotiator marked a softening in Tehran's tone towards a deal proposed last week by European countries, coming only a day after officials described the offer as "unbalanced".

"The European proposal for an unlimited suspension of uranium enrichment can be implemented, provided it does not contradict the Islamic republic's criteria," chief nuclear negotiator Hassan Rowhani said, quoted by state television.

Three European states offered Iran a deal Thursday under which Tehran would receive valuable nuclear technology if it indefinitely suspended all uranium enrichment activities, a key stage in the nuclear fuel cycle.

The three -- Britain, France and Germany -- hope that if Iran agrees to the deal it will be possible to stave off US demands for the nuclear issue to be sent before the UN Security Council.

Talks are due to resume in Vienna on Wednesday.

The International Atomic Energy Agency (IAEA), the UN's nuclear watchdog, has given Iran a November 25 deadline to allay concerns about its nuclear activities.

An IAEA spokeswoman said the agency's director Mohamed ElBaradei "believes that this is moving in the right direction, and we now welcome this constructive dialogue" between Iran and the EU.

British Prime Minister Tony Blair maintained a tough tone.

"I don't know anyone who is talking about military action in Iran or Syria," he said. "But what we are insisting on, quite rightly, is that there is a proper obligation on the Iranians to comply with international law and regulations.

"Now I don't think dialogue has been exhuasted on this at all, but we do need the Iranians to understand that the international community does not find it acceptable that they develop nuclear weapons," he said.

Rowhani however made clear that in Tehran's eyes suspending uranium enrichment indefinitely was not the same as imposing a permanent halt on the practice.

The term "unlimited does not mean permanent. The Europeans are talking about an unlimited (suspension) during the negotiations as it is forseen that long-term negotiations are starting with the Europeans."

"They say for example that if the negotiations last seven months, Iran must respect the suspension. We have always said that if the Islamic republic accepts the suspension at whatever level, this will be a voluntary decision."

Depending on the level of purification, enriched uranium can be used either as fuel for a civilian reactor or as the explosive core of a nuclear bomb. Iran strongly rejects US accusations it is seeking to manufacture atomic weapons.

Rowhani said Tehran would continue cooperating with the international community but insisted that Europe must also recognise its right to civilian nuclear technology.

"The Europeans must accept that our red lines and national rights cannot be violated," he said, according to the official IRNA news agency.

"Iran's patience to establish confidence with the world is great. It will not be exhausted at this early stage. We will calmly continue to work at winning confidence," Rowhani said.

"We are going to carry out any necessary action to create confidence as we want to work with the world in the areas of politics, economy, society and culture and we do not want to worry the world unnecessarily," Rowhani added.

Rowhani said the European proposal recogised the rights of Iran under the Nuclear Non-Proliferation Treaty, notably "the right of Iran to possess nuclear power stations".

Iran will continue cooperation with the IAEA, "not to make the Europeans happy but to prove the United States is lying when it says Iran is trying to manufacture a nuclear weapon", he said.

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