The White House on Wednesday reacted icily to Israeli Prime Minister Benjamin Netanyahu's plans to address Congress, an appearance sure to intensify opposition to a nuclear deal with Iran.

White House spokesman Josh Earnest suggested Netanyahu had broken with protocol in not informing President Barack Obama about the planned February 11 trip.

"We haven't heard from the Israelis directly about the trip at all," he said, adding the White House would "reserve judgment" about any possible face-to-face meeting until explanations are made.

"The typical protocol would suggest that the leader of a country would contact the leader of another country when he is travelling there. That is certainly how President Obama's trips are planned," said Earnest.

"So this particular event seems to be a departure from that protocol."

Israel and the United States are close allies, but personal relations between Obama and Netanyahu are said to be cool.

The pair have publicly clashed over Israeli settlement building in the West Bank and about how to tackle Iran's disputed nuclear program.

Obama's allies fear the trip could be used by Israel and by Republicans to rally opposition to a nuclear deal, undercutting years of sensitive negotiations just as they appear poised to bear fruit.

Washington and other global powers resumed talks with Iran last weekend in Geneva, with a view to having a framework deal in place by March.

The complex agreement would see Iran rein in its nuclear program, which the West believes is aimed at developing a bomb but which Tehran insists is for purely civilian use.

In his State of the Union address on Tuesday Obama argued a negotiated deal would secure "America and our allies - including Israel, while avoiding yet another Middle East conflict."

But Netanyahu has called Iran's nuclear push the most "vital national security challenge," his nation faces.

In December he said Israel -- long threatened by Iran -- would oppose an agreement that left the Islamic Republic as a "threshold nuclear power."

The Israeli premier had been invited to address a joint meeting of the Congress by Obama's Republican opponents, who also favor a tougher line against Tehran.

That includes further sanctions which Obama has threatened veto and which he says would "all but guarantee that diplomacy fails ."

House Speaker John Boehner insisted the invitation to Netanyahu was not designed to poke a finger in the US president's eye.

"There needs to be a more serious conversation in America about how serious the threat is from radical Islamic jihadists and the threat posed by Iran," said Boehner.

He described the Israeli leader as "a great friend of our country, and this invitation carries with it our unwavering commitment to the security and well-being of his people."

Netanyahu has addressed the US Congress twice before, in 1996 and 2011 The speech is scheduled to take place on February 11.

burs-arb/rcw