"We have to think together how long this dialogue should last," vice prime minister Silvan Shalom told army radio.

"What is certain is that neither Israel, nor the Arab countries, Europe and the United States can tolerate an Iran armed with a nuclear weapon," he said.

Six world powers led by Washington on Wednesday decided to invite Iran for direct talks on its nuclear programme which they suspect is aimed at making atomic weapons but which Tehran insists is civilian and purely peaceful.

Widely considered to be the Middle East's sole nuclear armed power, Israel considers Iran its arch-enemy because of repeated statements by President Mahmoud Ahmadinejad that the Jewish state should be wiped off the map.

Israel's new Prime Minister Benjamin Netanyahu has repeatedly said that Tehran's nuclear programme constituted the biggest concern to Israel, saying it was the biggest threat the Jewish state faced since its creation in 1948.

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