MOSCOW (AFP) - Israeli Prime Minister Benjamin Netanyahu on Thursday vowed Israel would never let Iran obtain a nuclear weapon, as world powers sought a deal with Tehran in Geneva over its nuclear drive.

"I pledge Iran will not get a nuclear weapon," Mr Netanyahu, who has never ruled out military action against Tehran, said in a Hebrew-language speech to leaders of Russia's Jewish community in Moscow. He did not elaborate.

Speaking on the second day of a visit to Moscow to campaign against an emerging world power deal with Iran, Netanyahu accused Supreme Leader Ayatollah Ali Khamenei of echoing the lexicon of the Nazi Holocaust.

"Yesterday, Iran's supreme leader, Khamenei, said 'death to America, death to Israel', he said that Jews are not human beings." "Sound familiar?" Mr Netanyahu asked.

"The Iranians deny our past and speak time afer time of their commitment to wipe the state of Israel off the map," he added. "That reminds us of the dark regimes which in the past began by persecuting us and later the whole of mankind,"

Khamenei told militia commanders in Tehran on Wednesday that Israel, Iran's arch-foe, was "doomed to collapse", "the rabid dog" of the Middle East, and had leaders "not worthy" of being called "human".

"That is the real Iran," Mr Netanyahu said. "Such an Iran must not get a nuclear weapon." After talks with Russian President Vladimir Putin on Wednesday, Mr Netanyahu insisted on the need for a "real" solution to the Iranian nuclear crisis.

Mr Netanyahu's speech in Moscow came as Iran and world powers were set Thursday to begin hammering out a landmark deal freezing parts of Tehran's atomic programme to ease fears of the Islamic republic obtaining nuclear weapons.

Tehran insists that its nuclear programme is entirely peaceful.

Netanyahu was due to visit Moscow's Jewish museum before heading home on Thursday night.