Iran will not retreat "one iota" from its nuclear program, Iranian President Mahmoud Ahmadinejad said on Tuesday just hours before his new chief negotiator was to meet Western diplomats for the first time.

The Rome talks, with European Union foreign policy chief Javier Solana, will be the first since Saeed Jalili's appointment on Saturday which might signal that Tehran has hardened its line on the nuclear program, analysts say.

But even ahead of the talks, due to start at 1600 GMT, Ahmadinejad rejected calls for Iran to suspend uranium enrichment, the key demand of the U.N. Security Council.

"We are in favor of talks but we will not negotiate with anyone about our right to nuclear technology," Ahmadinejad was quoted as saying by Iranian state television during a trip to Armenia. "Iran will not retreat one iota."

Iran's refusal to halt work that can be used to make fuel for power plants or, if it wants, material for warheads, has prompted the U.N. Security Council to impose two sets of sanctions.

Solana's spokeswoman, Cristina Gallach, said his mandate remained unchanged -- to explore the scope for entering formal negotiations with Iran on international requests that it halt sensitive nuclear activities.

"We have to be open to whoever they send," she said of Jalili's surprise appointment.

Solana had been in touch with U.S., Russian and Chinese officials ahead of the talks. "There have been intensive preparations for the meeting," she said.


Some Iranian officials have questioned the timing of changing the chief negotiator when the West is pushing for tougher penalties on Iran.

"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 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 National 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 "specializes in monologue", not debate. Jalili, who was a deputy foreign minister, toured European capitals in the past few weeks to discuss the nuclear dispute.

World powers have agreed to delay further penalties on Iran at least until November to see if Iran cooperates with U.N. International Atomic Energy Agency (IAEA) inspectors, and to await a report by Solana.

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

U.S. 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 U.N. measures. (Additional reporting by Parisa Hafezi and Zahra Hosseinian in Tehran and Mark John in Brussels)