If Washington and its allies do not stop Iran's nuclear programmes by force if necessary, Israel will, three Israeli legislators visiting the United States have warned.

"Israel will not live under the threat of an Iranian nuclear bomb. We feel we are obliged to warn our friends that Israel should not be pushed into a situation where we see no other solution but to act unilaterally against Iran," said Yosef Lapid, head of the Shinui Party.

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Lapid and his colleagues, Yuval Steinitz, chairman of the Knesset Foreign Affairs and Defence Committee, and Arieh Eldad, a member of the Israeli National Union Party, said conventional diplomacy will not work with Iran. "They won't be stopped unless they are convinced their programmes will be destroyed if they continue," they said.

Steinitz said Israeli officials estimate Tehran is only two to three years away from developing a nuclear bomb and that time is running out for the world to act.

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"We see an Iranian bomb as a devastating existential threat to Israel, to the entire Middle East, to all Western interests in the region," he said. "For us, either the world will tackle Iran in advance or all of us will face the consequences."

Eldad said Israelis across the political spectrum see Iran as the most serious threat to Israel, one that cannot be ignored.

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Eldad conceded that there could be problems if Israel acted - "If we have to do it, we will do it. If the United States and the world community do it, there is a chance the issue can be contained. If Israel has to do it alone, there is no chance the conflict can be contained."