Prime Minister Benjamin Netanyahu on Thursday accused Turkish Prime Minister Recep Tayyip Erdoğan of making a "dark and false" statement by calling Zionism a crime against humanity.
Erdoğan's statement, made at a U.N. meeting in Vienna on Wednesday, was also condemned by the head of Europe's main rabbinical group who called it a "hateful attack" on Jews.
"Just as with Zionism, anti-Semitism and fascism, it has become impossible not to see Islamophobia as a crime against humanity," Erdoğan said at the U.N. Alliance of Civilizations forum, according to Turkish media reports.
U.N. Secretary-General Ban Ki-moon also condemned the Turkish prime minister's comments on Friday, calling his statements "hurtful and divisive," and accusing him of adding to criticism of comments that risk deepening Turkey's rift with Israel.
Ban's spokesman said the secretary-general had heard Erdogan's speech at a U.N. meeting in Vienna on Wednesday through an interpreter.
"The secretary-general believes is it is unfortunate that such hurtful and divisive comments were uttered at a meeting being held under the theme of responsible leadership," the spokesman said in a statement.
Ties between Israel and Turkey have been frosty since 2010, when nine pro-Palestinian Turkish activists were killed in a clash with Israeli commandos aboard the Mavi Marmara, a ship that was part of a flotilla that tried to breach Israel's naval blockade of the Gaza Strip.
In recent weeks, there has been a run of reports in the Turkish and Israeli press about efforts to repair relations between the two countries, including a senior diplomatic meeting earlier this month in Rome and military equipment transfers.
The reports have not been confirmed by either government. No one was immediately available from Turkey's foreign ministry to comment on the new criticism of Erdoğan from Netanyahu and the European rabbinical group.
A statement from Netanyahu's office said he "strongly condemns (Erdoğan's) statement about Zionism and its comparison to Nazism."
The Zionist movement was the main force behind the establishment of the State of Israel.
"This is a dark and false pronouncement the likes of which we thought had passed into history," Netanyahu said.
Pinchas Goldschmidt, chief rabbi of Moscow and the head of the Conference of European Rabbis, said Erdoğan's criticism of Zionism amounted to anti-Semitism.
"This is an ignorant and hateful attack on the Jewish people and against a movement with peace at its core, which relegates Prime Minster Erdoğan to the level of (Iranian President) Mahmoud Ahmadinejad and, to Soviet leaders who used anti-Zionism as a euphemism for anti-Semitism," Goldschmidt said in an emailed statement.
"The irony of these comments will not be lost on the families of those slaughtered during the Armenian genocide, a crime still not recognized by the Turkish government," he added.
The White House also condemned the remarks.
"We reject Prime Minister Erdoğan's characterization of Zionism as a crime against humanity, which is offensive and wrong," White House spokesman Tommy Vietor said in a statement.
"We encourage people of all faiths, cultures, and ideas to denounce hateful actions and to overcome the differences of our times," he said.
Armenians accuse Ottoman Turks of committing an orchestrated campaign of massacres against Christian Armenians during World War I.
Turkey, which was established as a republic after the Ottoman Empire collapsed, denies those killings were genocide and says both sides lost lives in internecine fighting during the chaos of war.
The Conference of European Rabbis is an umbrella group of 700 religious leaders in Europe, where an estimated 1.7 millions Jewish people live. About 17,000 Jews live in Turkey, a country of 76 million people.