Jerusalem  - Sixty-three years after World War II, Israeli Prime Minister Ehud Olmert denounced persistent Holocaust denial Wednesday, as the country began a 24-hour commemoration of the Nazi's attempted genocide of the Jews of Europe.

"Sixty-three years have passed since the Satanic factories of death of the Nazis and their collaborators seized to operate, yet with the passing of time, the dimensions of the Holocaust still remain beyond comprehension, unfathomably shocking, unacceptably chilling," Olmert told a service at the Yad Vashem memorial centre in Jerusalem.

"Who would have believed that 63 years later, hatred of Jews and Israelis would rear its ugly head in so many different places around the globe, provocatively and venomously, inciting hatred?" he asked.

"The voices of those who deny the Holocaust are also being heard. To them, the haters, the deniers, and all the conspirators of evil and to all of those who allow them to function within their realms, we say today: This shall never happen again."

During the solemn service, six survivors lit six beacons, each commemorating a million Jewish victims.

As part of Israel's annual Holocaust Remembrance Day, a siren will also sound across the country at 10 a. m. (0800 GMT) Thursday and Israelis will stand at silent attention to honour the victims.

The names of the victims - or as many names as are known - will be read out at the Knesset and at Yad Vashem's Hall of Remembrance.

The United Nations has designated January 27, the day the Auschwitz death camp was liberated in 1945, as international Holocaust remembrance day, but Israel has traditionally marked it on the 27th day of the Jewish month of Nissan, one week before Independence Day, to symbolize the birth of the Jewish state from the ashes of the Holocaust.

According to counts held before and after the war, two-third of Europe's nine million Jews perished at the hands of the Nazis and their collaborators.(dpa)