BERLIN- Israeli Prime Minister Benjamin Netanyahu said on a visit to Germany on Thursday that one lesson Israel drew from the Holocaust was that threats to its existence could not go unchallenged and must be nipped in the bud.

German journalists handed the Israeli leader, in Berlin for talks with Chancellor Angela Merkel, a portfolio of 29 plans from the Auschwitz death camp discovered last year.

With his wife Sara at his side, Netanyahu said her father's family had been nearly wiped out by Nazis in World War Two.

We cannot allow evil to prepare the mass death of innocents. The most important thing to do is to nip it in the bud, said Netanyahu, alluding to past threats by Iranian President Mahmoud Ahmadinejad to wipe Israel off the map.

In their talks, Netanyahu and Merkel discussed Iran's disputed nuclear program, which Israel sees as a threat to its existence. Netanyahu is keen for tougher Western sanctions against Iran to halt Tehran's nuclear program.

Netanyahu said Allied powers had failed to act in time to prevent Nazis killing 6 million Jews in the Holocaust.

Armed barbarism knows no limits, he said. It has to be unarmed, disarmed in time.

He said it was important for leaders of other nations to recognize their own fate is imperiled by those who threaten our fate.

We cannot allow this to be repeated. We, means the whole civilized world. We cannot allow those who wish to perpetrate mass death, those who call for the destruction of the Jewish people to go unchallenged.

Western powers believes Iran's activities are aimed at developing a nuclear bomb but Iran says its program is aimed at civil nuclear energy.

The Holocaust remains a powerful emotional symbol casting a shadow over Israeli relations with Germany.

Before returning to Israel later on Thursday, Netanyahu is to visit the site of the 1942 Wannsee conference in Berlin, where Nazi leaders drew up plans for their so-called Final Solution to exterminate Jews.

Kai Diekmann, editor of Bild, Germany's top-selling newspaper, said as he handed Netanyahu the plans that there could never be a real normalization of German-Israeli relations after the Holocaust.

These plans remind us of a crime that with the passing of time seems ever more incomprehensible, Diekmann said, adding they were the original blueprints for the most inhumane project in mankind ... the plans of hell.

Bild newspaper has said the documents, which include architects' drawings of rooms including one marked Gaskammer, or gas chamber, are believed to have been discovered when a Berlin flat was cleaned out.

Accompanying Netanyahu on his trip to Germany is a government minister who lost his father and other family members at Auschwitz-Birkenau, the biggest concentration camp where at least 1.1 million Jews were killed.