The world could have faced destruction if Hitler had succeeded in acquiring nuclear weapons, Israeli President Shimon Peres said Wednesday at a Holocaust Memorial Day ceremony, calling on the world to shoulder today's responsibilities — a reference to Iran's nuclear program.

The ceremony at Yad Vashem, Israel's official Holocaust memorial and research center in Jerusalem opened the annual memorial day for the 6 million Jews killed in the Nazi Holocaust of World War II. Hundreds of Holocaust survivors and other Israelis filled the main plaza on a cool evening to listen to speeches, prayers and music, including a children's harmonica band founded by Shmuel Gogol, a survivor of the Warsaw ghetto.

Restaurants and places of entertainment closed throughout the country on Wednesday evening. After a memorial air raid siren on Thursday morning, further ceremonies were to include the public reading of names of Holocaust victims at sites around the country, including the Knesset, Israel's parliament.

Speakers at Wednesday's opening ceremony repeatedly referred to Israel's military strength, asserting that it could prevent another mass catastrophe from befalling the Jewish people.

Prime Minister Ehud Olmert lashed out at Holocaust deniers.

"Historical accuracy doesn't interest you," he said. "You want to negate the moral basis of the state of Israel. (But) Israel was not created because of the Holocaust," rather as an expression of the right of the Jewish people to its homeland.

Peres, 84, who won a Nobel Peace Prize in 1994 and serves now as ceremonial head of state, observed that the Jewish people might have been tardy in setting up their state, too late to rescue Jews from Europe.

Peres charged that the world woke up too late to eliminate the threat of Hitler before he started a war that killed 60 million people, warning that the world must not let that happen again. "In history, it is forbidden to be late," he said.

"My heart shudders when I recall that there was a possibility that Hitler could acquire nuclear weapons," he said. "A leader who plans mass destruction, together with weapons of mass destruction. What would have been left of our world?" he asked.

Aides confirmed that Peres was comparing Hitler and Nazi Germany to Iran and its president, Mahmoud Ahmadinejad, though Peres did not name either. Despite Iranian denials, Israel believes Iran is trying to build nuclear weapons, and Ahmadinejad has called repeatedly for Israel's destruction.

"We will act on our responsibilities," Peres said. "The world must act on its responsibilities without delay," he added, in what aides said was another reference to Iran.

In his speech, Peres criticized the German people of the 1930s for electing and venerating a "crazy person," Hitler. "How is it possible that a people does not rise up in the face of murder in the streets, an army rolling on tank treads to destroy neighbors of yesterday and friends of the day before?" he asked.

About 270,000 Holocaust survivors live in Israel, of whom about 80,000 survived Nazi death camps, according to Zeev Factor, chairman of a commission working on benefits for them. Many survivors live in poverty, and Factor said that despite Israeli government promises to increase their support payments, "nothing has been implemented yet."

In his speech at Yad Vashem, Olmert admitted, "We have not always paid our debt to the survivors."

The body that deals with German reparations and restitution, known as the Claims Conference, distributed or allocated $737 million to survivors in 2007, according to a statement. Some survivors charge that the body spends too much on education and research projects and not enough to help destitute survivors.