Israeli military intelligence chief Aviv Kochavi made a "secret visit" to Washington earlier this month to discuss the upcoming talks between world powers and Iran, a newspaper reported on Wednesday.
An Israeli security official confirmed the visit, which was reported in Haaretz newspaper, but could not provide further details.
As well as discussing Tehran's nuclear programme, the major general also held talks with senior White House and intelligence officials in New York and Washington on "the Syria crisis and Hezbollah's increasing power in Lebanon," the paper said.
Citing a senior Israeli official, Haaretz said Iran was the main topic, with talks focused on next week's talks between Tehran and the P5+1 powers -- the United States, Russia, China, Britain, France and Germany.
Israel and most of the West believe Iran's nuclear energy programme masks a drive to develop atomic weapons but the two allies disagree on how imminent the threat is. Tehran denies such intentions.
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US officials have warned against any pre-emptive military strike, with analysts predicting Iran could hit back at US and Israeli targets, with its Lebanese Shiite ally Hezbollah expected to launch rocket attacks on Israel.
According to the paper, Kochavi warned over Hezbollah's "increasing strength" and said internal tensions in Lebanon, combined with the instability in Syria, "increases the risk of escalation."
In recent weeks, Israel has spared no effort to ensure its concerns are well understood ahead of the May 23 P5+1 talks in Baghdad.
Earlier this month, National Security Adviser Yaakov Amidror toured European capitals meeting officials directly engaged in the Iran talks.
And last week, EU foreign policy chief Catherine Ashton made a surprise visit to Jerusalem to discuss the talks with top Israeli officials.
On Tuesday, Defence Minister Ehud Barak flew to Washington for the third time in recent months for talks with his American counterpart, which were also expected to deal with Iran.
Before leaving, Barak complained that the world's demands of Iran were "minimalist" and would not succeed in making it halt its nuclear drive.