American officials have accused Israel of spying on diplomatic talks between the United States and Iran – and then feeding sensitive information back to Barack Obama’s political opponents in America.

Israel, which says the allegation are “utterly false”, is opposed to an emerging deal on Iran’s nuclear programme, as are most members of the Republican Party – the sworn political opponents of Mr Obama’s Democratic Party.

According to US newspaper the Wall Street Journal, US spies monitoring Israeli communications claim to have intercepted information which they allege could only have come from spying on American talks about Iran’s nuclear programme.

Spying is commonplace in international affairs, but the claim that Israel was feeding information to opposition legislators in the US Congress appears to have angered the Barack Obama’s administration.

“It is one thing for the US and Israel to spy on each other. It is another thing for Israel to steal US secrets and play them back to US legislators to undermine US diplomacy,” an unnamed US official reportedly told the newspaper.

Benjamin Netanyahu spoke against an emerging deal with Iran at a a joint session of US Congress (Reuters)

An Israeli spokesperson told the BBC, however: “These allegations are utterly false. The state of Israel does not conduct espionage against the United States or Israel's other allies. The false allegations are clearly intended to undermine the strong ties between the United States and Israel and the security and intelligence relationship we share.”

Earlier this year Republicans unilaterally invited Israeli prime minister Benjamin Netanyahu to address the US Congress, a move which angered Democrats and led to a boycott of the session.

Mr Netanyahu used the opportunity to warn the US against a nuclear deal, arguing that Iran was on a “march of conquest, subjugation and terror”.

The spying allegation comes amid a noticeable cooling of relations between the United States and Israel.

On Monday the White House made its strongest call yet for Israel to end its 50-year illegal occupation of Palestine.

“Israel cannot maintain military control of another people indefinitely,” White House chief of staff Denis McDonough told a meeting of liberal American pro-Israel lobbyists, J-Street. “An occupation that has lasted for almost 50 years must end.”

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The spying allegations come the same week as claims that Israeli intelligence services spied on Tony Blair when he was prime minister.

In his new book, Mr Blair’s former communications mastermind Alastair Campbell says the prime minister had indicated that he believed his car was bugged by Israeli agents during a 1998 visit to the country. Israel says it does not spy against its allies.

Iran also blames the Israeli intelligence agency Mossad for a series of bomb and gun attacks targeting Iranian professors specialising in nuclear science.

In 2012 a magnetic bomb thrown by a group of motorcycle riders in Tehran killed a university professor specialising in nuclear science.

Mr Obama said US-Iranian relations were on the path to improvement (The White House)

In 2010 another scientist was killed by a remote controlled bomb attached to a motor bike, while in July 2011 an Iranian academic was shot by attacks, also riding motorcycles.

At the time of the 2012 attack a spokesperson for the Israel Defense Forces said: “I don't know who settled a score with the Iranian scientist, but I am certainly not shedding a tear.”

In a video message to the Iranian people last week wishing them a happy Iranian New Year, Mr Obama said the two countries were facing an “early spring” in their relationship.

“This year we have the best opportunity in decades to pursue a different future between our countries, he said.

“Just over a year ago we reach an initial understanding regarding Iran’s nuclear programme and both sides have kept our commitments.”

He said Iran had halted progress on its nuclear programme and even rolled it back in some areas.