Israeli leaders and survivors have attended a wreath-laying ceremony at Jerusalem's Yad Vashem memorial to commemorate the six million Jews who died in the Holocaust.

During the ceremony, known as "Every person has a name", survivors lit memorial candles and read the names of loved ones killed during World War II.

To pay homage to the victims of the Nazi genocide, a two-minute siren sounded across the country. In homes and businesses people stopped what they were doing as a sign of respect.

Israeli prime minister Benjamin Netanyahu sparked criticism for a speech at the ceremony in which he compared the perceived threat of Iran's nuclear ambitions to the Nazi genocide.

"Those who dismiss the Iranian threat as a whim or an exaggeration haven't learned a thing from the Holocaust," he said.

"A nuclear Iran is an existential threat to the state of Israel and also the rest of the world," he said. "We have an obligation to prevent Iran from obtaining nuclear weapons. It's the world's obligation, but above all it is our obligation."

Opposition leader Tzipi Livni said it was inappropriate to use the analogy. Haaretz newspaper criticised the politicised use of the Holocaust in an editorial.

Israel's president, Shimon Peres, told the dramatic story of the Nazi crackdown on Jews on the Polish village of Wiszniewo where his family used to live hidden into a synagogue.

"The gates were locked and they were burned alive," he said. "According to one testimony, a woman who remained called on the Jews to run. But they were all shot. No one survived.

"Holocaust deniers are denying the actions of their predecessors to cover up for their own actions. The lie of denial will not extinguish the fire of the inferno."

The annual remembrance is one of the most solemn celebrations in Israel. Restaurants, cafes and places of entertainment closed down, and radio and TV aired documentaries about the Holocaust.

Israel marks the annual Holocaust and heroism remembrance day on 19 April, the 27th of the Jewish month of Nissan, the anniversary of the first day of the Warsaw ghetto uprising in 1943 when tens of thousands of Jews rose up against the Nazis.