Prime Minister Benjamin Netanyahu defended on Sunday a planned speech to the U.S. Congress about Iran, saying he had a moral obligation to speak out on an issue that poses a mortal threat to Israel.

His visit to Washington in March has opened up a rift with the White House and has drawn accusations in Israel that Netanyahu is undermining the country's core foreign alliance in an effort to win an election due two weeks after the trip.

Briefing his Cabinet on the March 3 speech to a joint meeting of Congress, Netanyahu said his priority was to urge the United States and other powers not to negotiate an Iranian nuclear deal that might endanger Israel.