Some 20,000 people from around the world, Jews and non-Jews, set off under grey skies on Thursday to make their way from the main camp to Birkenau, where at least 1.1 million men, women and children, most of them Jews, were exterminated by the Nazis.

At Birkenau, they were to take part in a remembrance ceremony, hearing speeches by Israeli Prime Minister Ariel Sharon, Polish Prime Minister Marek Belka and former Auschwitz inmate, Jewish scholar and writer Elie Wiesel, all doubtless driving home the message that the world has a duty to remember the Holocaust, and to never let it happen again.

Sharon arrived at noon in southern Poland with 20 Holocaust survivors and 20 of their grandchildren who are serving in the Israeli army. "I am naturally very moved to be on the spot where the worst happened," Sharon told journalists accompanying him on his plane.

Survivors revisit torture chambers

At Auschwitz, thousands crowded into the camp, touring its gas chambers, torture cells, execution wall, the barracks into which the Nazis crammed the first inmates.

"I had to come here to see where my people were murdered," an elderly woman from the southern US state of Florida told AFP, before breaking off abruptly, her voice wracked by sobs. "Now I see it and it's horrible," she said, apologizing for her tears.

Irene Zattfild, of Hungarian Jewish extraction, was taking part in her fifth March of the Living. She was interned at Auschwitz when she was 13 and lost her entire family here. "I feel very, very lucky to have survived. I'm the only survivor in my family. Now I bring people here," she said, her face almost permanently creased in a smile. "I love life, and I want to pass that message on to others," Irene said.

Hungary only began mass deportations of Jews late in the war, but once they began they were carried out with horrifying efficiency. Some 450,000 Hungarian Jews were killed at Auschwitz, many sent directly to their deaths as soon as they arrived at the camp, packed like animals into cattle cars.

"We did not reach out to the victims, we were not strong enough," Hungarian Prime Minister Ferenc Gyurcsany said at a private ceremony for his country's victims. "These atrocities were committed by no one other than us all, the human race," he said.

"This must not happen again"

Other marchers had come from Australia, Canada, France, Greece, Mexico, Poland, South Africa and beyond. Together, young and old, Jewish and non-Jewish, made their way under a grey sky and light drizzle out of Auschwitz to Birkenau to remember the victims of the Holocaust.

The festival atmosphere that had reigned before the shofar sounded was replaced by near silence, punctuated by thousands of footsteps on the dirt paths and cobbles leading out of Auschwitz.

"This is a reunion of a whole nation and those people who died here," said Eugenia Spector, a 19-year-old Ukrainian Jew from Odessa. She said the laughter and song before the march was a way of letting off tension. "Some of the laughter and joking is just to relax. When we went to the gas chamber, we had the feeling we were going to be gassed at any second. After we visited the camp, we felt nervous and didn't know what to do, and we got rid of the tension by laughing, almost hysterically," she said.

Jurek Sternfeld, 66, was in a group of 160 Jewish people from around Australia. Born in Warsaw, six months before Nazi Germany invaded Poland starting World War II, the most deadly conflict in history, he was smuggled out of Poland by his mother immediately after the start of the war. His family spent the war in the Soviet Union, and survived the conflict intact -- a rarity for Polish Jews.

"I think this march is the right thing, as far as the future is concerned, to remember what happened. As far as I'm concerned this was the blackest point in the history of humankind. A whole group of people was deliberately being wiped out. This must not happen again and this is what motivates me to come here," he said.

The March of the Living

Half an hour after the march had started, the crowd was still passing under the infamous Arbeit Macht Frei gate at Auschwitz and across the dirt paths of the camp onto the tarmacked road leading to Birkenau, three kilometers (two miles) away.

There, a memorial ceremony was to be held in the midst of the rubble of the purpose-built interconnecting gas chambers and crematoria.

A group of Roman Catholic school teachers from the United States was also among the marchers. "The march is a chance for us to show that we remember and to be here on such a historical occasion -- the 60th anniversary of the end of the war," said Toby Harkleroad, a teacher from Washington DC. "We'll take the message back to our students and everyone we meet in our lives, to make sure we never forget and it never happens again. Especially as Catholics, we have to look back at the role we might have played in setting the world up for such a tragedy happening, what we did or did not do," he said.

Wartime Pope Pius XVI did not denounce the Nazi persecution of the Jews.

The Nazis exterminated six million European Jews, half of them from mainly Catholic Poland, home to Europe's largest Jewish community before World War II.

The March of the Living began in 1988 to counter voices denying that the Holocaust ever took place.