At the United Nations in September, Netanyahu drew a red line across a cartoon bomb to illustrate the point at which Iran will have amassed enough uranium to fuel one nuclear bomb. He said Iran could reach that threshold by mid-2013.

Netanyahu also said Iran was building faster centrifuges that could allow it to speed up its enrichment activities.

Israel, widely believed to be the Middle East's only nuclear-armed power, has issued veiled warnings for years that it might attack Iran if international sanctions and diplomacy fail to curb Tehran's nuclear ambitions.

Israel has long insisted on the need for a convincing military threat and setting clear lines beyond which Iran's nuclear activity should not advance.

"I think it's important to note that we (Israel) can't allow it to happen. Our clocks are ticking at a different pace. We're closer than the United States, we're more vulnerable, and therefore we'll have to address this question of whether to stop Iran before the United States does," Netanyahu said.

The Israeli prime minister said he was concerned that the military conflict in Syria and the political crisis in Egypt had pushed the Iran nuclear issue lower on the international agenda.

"There are many important issues that we have to deal with and I have a sense that there is no sense of urgency on Iran and yet Iran is the most important and the most urgent matter of all," he said.