JERUSALEM, May 16 (Reuters) - The United States and Israel agree on the need for "tangible action" to prevent Iran from developing nuclear weapons, Israeli Prime Minister Ehud Olmert's spokesman said after a visit by U.S. President George W. Bush.

"We are on the same page. We both see the threat ... And we both understand that tangible action is required to prevent the Iranians from moving forward on a nuclear weapon," Olmert spokesman Mark Regev said on Friday.

Regev described diplomatic efforts so far to exert pressure on Iran as "positive", but added: "It is clearly not sufficient and it's clear that additional steps will have to be taken".

Asked about the option of using military force, Regev said: "Leaders of many countries have talked about many options being on the table and, of course, Israel agrees with that."

Bush ratcheted up his rhetoric toward Tehran in a speech to Israel's Knesset on Thursday, saying critics' calls for talks with Iranian President Mahmoud Ahmadinejad were comparable to the "appeasement" of Adolf Hitler before World War Two.

Bush vowed that Washington would stand with Israel in opposing Iran's nuclear ambitions, saying it would be "unforgivable" if Tehran were allowed to get the bomb.

Iran has said it will not stop uranium enrichment, which it says is for generating electricity only. In a separate development on Friday, the United States said it would sign an agreement with Saudi Arabia to help the kingdom develop peaceful nuclear energy. (Reporting by Adam Entous; Editing by Mark Trevelyan)

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