German Nobel literature laureate Gunter Grass touched off a firestorm of protest Wednesday with a poem accusing Israel of plotting Iran's annihilation and threatening world peace.

The 84-year-old longtime leftist activist wrote in "What must be said" that he worried Israel "could wipe out the Iranian people" with a "first strike" due to the threat it sees in Tehran's disputed nuclear programme.

"Why do I only say now, aged and with my last ink: the atomic power Israel is endangering the already fragile world peace?" reads the poem, which appeared in the daily Sueddeutsche Zeitung on Wednesday.

Grass answers that Nazi Germany's "incomparable" crimes against Jews and his own fear of accusations of anti-Semitism kept him from openly criticising Israel.

But now, "tomorrow could already be too late" and Germany could become a "supplier to a crime", Grass wrote, referring to a deal sealed last month for Berlin to sell Israel a sixth nuclear-capable Dolphin-class submarine.

"I admit: I will be silent no longer, because I am sick of the hypocrisy of the West".

Israel slammed the poem, which also sparked a fevered debate on German-language news and culture websites.

"What must be said is that it belongs to European tradition to accuse the Jews of ritual murder before the Passover celebration," said Emmanuel Nahshon, Deputy Chief of Mission at the Israeli embassy in Berlin, in a statement.

"It used to be Christian children whose blood the Jews used to make matza (unleavened bread), today it is the Iranian people that the Jewish state purportedly wants to wipe out."

Nahshon said Israel was "the only state in the world whose right to exist is publicly doubted".

"We want to live in peace with our neighbours in the region. And we are not prepared to assume the role that Gunter Grass assigns us in the German people's process of coming to terms with its history."

The Israel director of the Nazi-hunting Simon Wiesenthal Centre, Efraim Zuroff, accused Grass of making himself the spokesman "for anti-Semitic Germans sick of the Holocaust and seeking to rid themselves of any responsibility for its aftermath".

German Foreign Minister Guido Westerwelle released a statement without mentioning Grass by name in which he warned against "making light of the dangers of the Iranian nuclear programme".

"Iran obtaining nuclear weapons is not only a threat to Israel and the entire region but also a danger for the world's security architecture," he said, underlining Germany's efforts to prevent Iran from having nuclear arms.

Grass, author of the renowned anti-war novel "The Tin Drum", shocked his admirers in 2006 when he admitted, six decades after World War II, that he had been a member of the notorious Waffen SS -- a revelation that severely undermined his until then substantial moral authority in Germany.

Henryk M. Broder, a prominent German Jewish columnist, accused Grass in light of his poem of having become "the prototype of the educated anti-Semite".

"Grass has always had a problem with Jews but he has never articulated it as clearly as with this 'poem'," Broder wrote in the daily Die Welt.

The country's most influential media commentators were unanimous in their criticism, saying Grass had offered up a one-sided portrayal of Israel as the aggressor and Iran as a victim of a mortal threat.

"Never before in the history of the republic has a prominent intellectual waged a battle against Israel in such a cliche-ed way," wrote the website of news weekly Der Spiegel.

Only Wolfgang Gehrcke of the far-left Die Linke party defended Grass in public, saying he had the "courage" to express "what is widely kept silent".

Israel, the sole if undeclared nuclear power in the Middle East, has said it is keeping all options open for responding to Iran's programme which it says is aimed at securing atomic weapons, posing an existential threat to the Jewish state.

Iran, whose President Mahmoud Ahmadinejad frequently questions Israel's right to exist, has consistently denied that its sensitive nuclear work is aimed at making weapons.