A leaked memo appearing to show Tehran's efforts to design an atomic bomb trigger was forged by the US, Iran's President Mahmoud Ahmadinejad told a US news programme.

Ahmadinejad was asked by ABC News about a report in London's Times newspaper last week on what it said was a confidential Iranian technical document describing a four-year plan to test a neutron initiator, the part of a warhead that sets off an explosion.

"They are all fabricated bunch of papers continuously being forged and disseminated by the American government," he told the US network in an interview broadcast on Monday.

Reports that Iran is working on a bomb trigger are "fundamentally not true", Ahmadinejad said.

On December 14, The Times published what it said was the Farsi-language document, with an English translation, entitled "Outlook for Special Neutron-Related Activities Over the Next Four Years".

The document described steps to develop and test parts for a neutron initiator, a device that floods the core of highly enriched uranium with subatomic particles to set off the chain reaction of a nuclear explosion.

Last week, Iranian Foreign Ministry spokesman Ramin Mehmanparast called the report "baseless ... not worthy of attention, intended to put political and psychological pressure on Iran".

"Arrogant powers"

Iran, the world's No. 5 oil exporter, says its uranium enrichment programme is aimed at generating electricity so that it can export more gas and oil. Because of its record of nuclear secrecy, the West believes Iran wants to make atomic bombs.

In a televised speech in southern Iran on Tuesday, Ahmadinejad said the nuclear arsenals of the United States and Israel should be dismantled. The Jewish state is assumed to have the Middle East's only atomic weapons.

"They must know that the Iranian nation and all the world's nations will continue resisting until the complete (nuclear) disarmament of America and all arrogant powers," he told a crowd at a stadium in the city of Shiraz.

Dismissing Western allegations about Iran's nuclear ambitions, Ahmadinejad said: "You should know that if we had any intention of building a bomb, we would have had enough guts and courage to announce that without any fear from you."

Iran appears to be on course to miss the West's year-end deadline for it to accept an enrichment fuel deal aimed at calming international fears about its nuclear programme.

If that happens, Washington has made clear it intends to pursue harsher sanctions against Iran in the UN.

Ahmadinejad said in Shiraz: "Who are they to set us a deadline? We set them a deadline that if they do not correct their attitude and behaviour and literature we will demand from them the Iranian nation's historic rights." – Reuters