His visit comes amid talks between the IAEA and Iran aimed at resolving questions over the history of its nuclear programme, which the West fears could be diverted to weapons use.

Mohammad Saeedi, the deputy head of the IAEO, said: "Regarding the active cooperation of Iran with the IAEA, and resolving ... important matters about Iran's nuclear issue, Tehran's relations with the agency have entered a new phase."

Final conclusions 

Despite a four-year investigation into Tehran's atomic drive, the IAEA has never been able to confirm whether the programme is peaceful.

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The aim of its latest talks with Tehran is to finally draw this investigation to a conclusion.

Ahmad Khatami, a cleric, told worshippers in Tehran during Friday prayers: "We hope that ElBaradei, after seeing the reality, will make a positive and realistic report and close our case completely at the agency."

ElBaradei, who is accompanied by Olli Heinonen, the IAEA deputy director-general, is due to hold a news conference with Aghazadeh at 1230 GMT.

It is possible he will hold talks with supreme leader Ayatollah Ali Khamenei on Saturday.

Sanctions insisted 

A recent US intelligence report said Iran halted a nuclear weapons programme in 2003, undermining repeated accusations from George Bush, the US president, that Tehran was actively seeking the atomic bomb.

The report appears to have momentarily taken the heat out of the crisis, but Washington still wants the UN Security Council to adopt a third set of sanctions against Tehran.

The UN Security Council has repeatedly called on Iran to freeze the process of uranium enrichment - which can be used both to make atomic fuel and a weapons.

But Iran has repeatedly said it has a right to the full nuclear fuel cycle and insists its nuclear programme is solely aimed at generating electricity for a population whose fossil fuels will eventually run out.