Washington (AFP) - The top Republican in Congress said Tuesday he was "shocked" by a report that Israel spied on Iranian nuclear talks but insisted he did not know whether information was shared with US lawmakers.

The Wall Street Journal reported late Monday that in addition to Israelis spying on the highly-sensitive negotiations between Tehran and world powers, details were back-chanelled to US legislators in an effort to sabotage the deal intended to limit Iran's nuclear program.

"Frankly I was a bit shocked, because, there was no information revealed to me whatsoever," said House Speaker John Boehner, who will visit Israel in coming weeks following Prime Minister Benjamin Netanyahu's re-election victory.

On the apparent leaking of details to unnamed members of Congress, Boehner said,"I'm not aware of that at all."

Many Republicans are opposed to any accord that would not outright eliminate Iran's entire nuclear program, rather than merely freeze or contain it.

Israel's outgoing Foreign Minister Avigdor Lieberman dismissed the Journal report as untrue, adding that "we do not spy on the United States."

Boehner avoided commenting on the appropriateness of Israelis potentially transferring sensitive negotiation data to members of Congress, saying only that he was "not sure what the information was -- but I'm baffled by it."

Boehner infuriated Democrats earlier this year when he arranged for Netanyahu to address a joint meeting of Congress on the nuclear negotiations, without consulting with the White House.

Several Democratic lawmakers boycotted the speech, in which Netanyahu warned of the perils of agreeing to an imperfect deal with Iran, and President Barack Obama declined to meet with the Israeli leader during his Washington visit.

Boehner travels to Israel during the congressional Easter recess, which begins late this week, although his office did not provide specific dates.

He is expected to lead a Republican congressional delegation to Israel and meet with Netanyahu.

A spokesman said Boehner "looks forward to visiting the country, discussing our shared priorities for peace and security in the region, and further strengthening the bond between the United States and Israel."