"Iran considers that suspension is neither a pre-condition to nor the result of negotiations," Javad Vaidi, deputy secretary of Iran's Supreme National Security Council, told AFP.

The five permanent UN Security Council members -- Britain, China, France, Russia and the United States -- plus Germany have offered Iran a package of incentives if it agrees to temporarily halt uranium enrichment.

That work is at the centre of fears the hardline regime could acquire nuclear weapons, though Tehran insists it is only to provide fuel for nuclear energy.

Vaidi was speaking by telephone from Vienna, where he said Thursday night that having nuclear weapons "would go against the national interest of Iran's security."

At a meeting organised by Austria's far-right Freedom Party, he said that if Iran owned nuclear weapons the United States would gather the country's neighbours "under a military umbrella" against Tehran, according to the APA news agency.

That would give Israel a pretext to back weapons of mass destruction, he said.

Diplomats have said Iran was asked to reply by June 29 to the offer of incentives, but Iranian President Mahmoud Ahmadinejad said Wednesday Tehran would take until August 22 to answer.

Vaidi said the conditional offer contained "fundamental uncertainties".

"Everything depends on the formula: to know who is ready for what and when to guarantee Iran's right to continue developing peaceful nuclear technology," he said, rejecting any possible ultimatum from the United States.

Vienna's Jewish community protested Thursday against Iran's participation in the meeting.

Iranian President Mahmoud Ahmadinejad, who has previously called for Israel to be "wiped off the map", said in China last week there needed to be an independent investigation into the Holocaust.