Israeli President Shimon Peres on Wednesday told the visiting head of the UN's atomic watchdog that his organization must respond with "severity" to Iran's nuclear ambitions and its threats against the Jewish state.

Greeting Yukiya Amano on his first visit to Israel since becoming head of the International Atomic Energy Agency last December, Peres praised changes the new chief had made to the institution and took a thinly-veiled swipe at his predecessor, Mohamed ElBaradei.

"As a result of this substantive change Israel feels has taken place at the IAEA, we can speak this morning professionally and in a friendly atmosphere. From our perspective this is a new experience," Peres' office quoted him as telling Amano.

Israel, the United States and other Western countries believe that Iranian President Mahmoud Ahmadinejad ultimately seeks to build a nuclear arsenal.

Iran, which on Saturday began loading fuel into its Russian-built first nuclear power plant, denies the allegations, saying its programme is for civil energy purposes only.

"The statements of Ahmadinejad calling for the destruction of Israel and denying the Holocaust are unprecedented in the diplomatic world and international community," the president said.

"The IAEA should treat them with the required severity," added Peres, who is considered to be the father of Israel's own nuclear programme.

Amano's visit comes against a backdrop of demands by some IAEA members that Israel, generally considered to be the Middle East's sole if undeclared nuclear-armed power, sign the international Non-Proliferation Treaty.

The Haaretz daily reported on Tuesday that Prime Minister Benjamin Netanyahu had snubbed Amano by last week abruptly cancelling a meeting that was scheduled months ago.

US President Barack Obama last month assured Netanyahu that a proposed 2012 conference on establishing a nuclear weapons-free Middle East would not single out Israel.

Wednesday's statement from Peres' office quoted Amano as saying that he had so far met Strategic Affairs Minister Moshe Yaalon and visited the Soreq Nuclear Research Centre, whose activities are monitored by the IAEA.

The presidential statement added that Shaul Horev, head of the Israel Atomic Energy Commission, also took part in Wednesday's talks.