Nobel Prize-winning writer Gunter Grass has criticised Israel for "endangering the already fragile world peace".
Mr Grass, 84, is known for his left-wing political views. In a poem published in the German newspaper Sueddeutsche Zeitung, he expressed concern that Israel "could wipe out the Iranian people" if it took action against Tehran's nuclear ambitions.
The anti-war writer, who was at the centre of a controversy in 2006 after it emerged that he had served in the Waffen SS during the Holocaust, said in the poem that he was "tired of Western hypocrisy". He said he had remained silent on Israel for years because of his past.
He also accused German y of being "supplier to a crime" following an agreement with Israel to sell a nuclear-capable Dolphin-class submarine.
"I will be silent no longer," wrote Mr Grass.
Emmanuel Nahshon, deputy chief of mission at the Israeli embassy in Berlin, condemned Mr Grass's attack. "It belongs to European tradition to accuse the Jews of ritual murder before the Passover celebration," he said. "It used to be Christian children whose blood the Jews used to make matza, today it is the Iranian people that the Jewish state purportedly wants to wipe out.
"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."
A spokesman for Angela Merkel said: "In Germany, the freedom of artistic expression applies, as, fortunately, does the freedom of the government not to comment on every work of art,"
The Central Council of Jews in Germany said the poem was an "aggressive pamphlet of agitation", while Mr Grass was accused of being "the prototype of the educated antisemite" by German Jewish commentator Henryk Broder.
"Grass has always had a problem with Jews but he has never articulated it as clearly as with this 'poem,'" he wrote in a piece for Die Welt. "Haunted by feelings of guilt and shame and also driven by the desire to settle history, he is now attempting to disarm the 'cause of the recognisable threat'."