Israel says Iran lied on nuclear arms, pressures U.S. to scrap deal

* Netanyahu presents files but experts see no "smoking gun"

* Pompeo says information shows Iran's leaders lied about "Project Amad"

* Iran calls Israeli leader "boy who cried wolf" (Recasts with comments from Pompeo, White House official)

By Stephen Farrell and Lesley Wroughton

TEL AVIV/WASHINGTON, April 30 (Reuters) - Israeli Prime Minister Benjamin Netanyahu unveiled on Monday what he said was evidence of a secret Iranian nuclear weapons program that could step up pressure on the United States to pull out of a 2015 nuclear deal with Iran.

U.S. Secretary of State Mike Pompeo said the information showed that Iran's leaders lied to their people about a nuclear weapons program known as "Project Amad". But Pompeo declined to say whether the documents provided evidence of a violation of the nuclear deal.

Intelligence experts and diplomats said Netanyahu's presentation, in a prime-time television presentation, did not seem to have a "smoking gun" showing a violation by Iran but it could strengthen the hand of advisers to U.S. President Donald Trump who want to scrap the nuclear agreement.

Most of the purported evidence Netanyahu presented dated to the period before the 2015 accord was signed, although he said Iran had also kept important files on nuclear technology since then, and continued adding to its "nuclear weapons knowledge".

Tehran dismissed Netanyahu as "the boy who cried wolf", and called his presentation propaganda.

As he traveled back from Amman, Jordan, to Washington on Monday, Pompeo told reporters he and Netanyahu discussed the documents in Tel Aviv during a meeting on Sunday.

Pompeo said that while the existence of the Amad nuclear project was known for some time, the new material discovered by the Israelis will help better understand the scope and scale of the program.

He added that the documents make "very clear that at the very least the Iranians have continued to lie to their own people.”

Asked whether the information indicated a violation of the Iran nuclear agreement, Pompeo responded: “I‘ll leave that to lawyers. The president will ultimately have to make a determination about that too.”

Trump has threatened to pull the United States out of the international deal unless it is renegotiated by May 12. After Netanyahu spoke, Trump repeated his criticism of the deal, suggesting he backed the Israeli leader's remarks.

At Israel's Defence Ministry, Netanyahu stood in front of stacks of files representing what he described as a vault full of Iranian nuclear documents obtained weeks before.

"Iran lied about never having a nuclear weapons program," he said. "One hundred thousand secret files prove it did. Second, even after the deal, Iran continued to preserve and expand its nuclear weapons knowledge for future use."