Israeli Prime Minister Benjamin Netanyahu will repeat his warnings about the potential threat of a nuclear-armed Iran when he addresses the U.N. General Assembly Thursday.

Mr. Netanyahu's speech comes amid speculation that Israel could launch a pre-emptive military strike against Iran. The Israeli leader has demanded that U.S. President Barack Obama spell out non-negotiable points, or “red lines,” that would justify an attack. The demand has been rejected but Mr. Obama has stressed that the U.S. will do what is necessary to prevent Tehran from getting a nuclear weapon.

In his speech to the General Assembly Wednesday, Iranian President Mahmoud Ahmadinejad issued a veiled condemnation of Israel as “uncivilized Zionists.” Mr. Netanyahu issued a statement before leaving his country denouncing Mr. Ahmadinejad's remarks, which were delivered on Yom Kippur, one of the holiest days on the Jewish calendar.

He described Iran as “a dictatorial regime that strives, at every opportunity, to wipe us off the map.” Mr. Netanyahu promised that he is “working in every way” to prevent Iran from possessing nuclear weapons.

Iran is under U.N. sanctions for its controversial nuclear program. World powers suspect Iran is seeking to develop nuclear weapons but Tehran says its nuclear goals are peaceful.

Also speaking before the U.N. General Assembly Thursday will be Palestinian President Mahmoud Abbas, who is expected to ask the world body to recognize Palestine as an observer state. Mr. Abbas used his 2011 speech to launch a historic bid to gain the territory full membership in the United Nations, which was rejected.

The Palestinian delegation will likely delay pushing the new initiative until after the U.S. presidential elections in November.