Iran's new nuclear negotiator headed to Rome on Tuesday to meet Western diplomats who will try to gauge whether Tehran has hardened its stance on its atomic programme.

The talks had been scheduled to be between European Union foreign policy chief Javier Solana and Ali Larijani whose resignation as Iran's chief nuclear negotiator was announced on Saturday.

Larijani will now attend with his replacement, Saeed Jalili, a close ally of President Mahmoud Ahmadinejad who has vowed not to compromise on Iran's pursuit of nuclear technology.

Analysts have said Jalili's appointment might signal a hardening of Tehran's position over its nuclear plans.

Ahmadinejad unexpectedly cut short his visit to Armenia on Tuesday to return home, the Armenian presidential press service said. Russia's Itar-Tass news agency quoted unidentified sources as saying Ahmadinejad's decision was prompted by 'unexpected developments in Iran'.

 Iran's refusal to halt work that can be used to make fuel for power plants or, if Iran wanted, material for warheads has already prompted the UN Security Council to impose two sets of sanctions. Iran insists its plans are peaceful.

'The senior delegation of Iran's nuclear negotiators left for Rome to take part in the fourth round of nuclear talks with EU foreign policy chief Javier Solana,' Iran's official IRNA news agency said.

There has been no breakthrough on the dispute in previous rounds of talks between Solana and Larijani.

 The meeting at the lavish Doria Pamfili villa is scheduled for 1600 GMT. Solana's office said there would be a 'short statement' issued to reporters afterwards to discuss Iran's nuclear programme.

Some Iranian officials have questioned the timing of changing the chief negotiator when the West is pushing for tougher penalties on Iran for not heeding UN demands to suspend uranium enrichment activities.

'In the sensitive and important conditions in which the nuclear issue is (now) being studied, it would have been better if such important changes did not happen,' said Ali Akbar Velayati, international affairs adviser to Supreme Leader Ayatollah Ali Khamenei.

Although Ahmadinejad is Iran's most public voice on atomic policy, Khamenei has the final say in all state matters.

Analysts say Khamenei would have had to approve Jalili's appointment, indicating his support for the president's tough line.

Jalili has taken over as secretary of Iran's Supreme Natioal Security Council, traditionally also the chief atomic negotiator. Larijani is still on the council as one of two representatives of the supreme leader.

Some diplomats have been wary about the choice of Jalili for negotiator. One said he 'specialises in monologue' not debate.

Jalili, who was a deputy foreign minister, toured European capitals in recent weeks to discuss Iran's nuclear row.

World powers have agreed to delay further penalties on Iran at least until November to see if Iran cooperates with UN.

International Atomic Energy Agency (IAEA) inspectors, and to await a report by Solana.

Tehran insists its nuclear programme is aimed at producing electricity so it can preserve more of its massive oil and gas reserves for export.

US President George W Bush has said a nuclear-armed Iran could lead to a third world war. France is pushing for stronger European Union sanctions against Tehran, as well as pressing for further UN measures. - Reuters