OSWIECIM, Poland (Reuters) - World leaders and survivors stopped to remember the horror of the Holocaust on Thursday at a snow-swept ceremony in Auschwitz-Birkenau on the 60th anniversary of the liberation of the Nazi death camp.

Surrounded by barbed wire fences and remnants of the killing machine used to gas and incinerate some of the six million Jews who died in the Holocaust, the leaders vowed that the World War II atrocity must never be forgotten.

Up to 1.5 million people died in the gas chambers and crematoria of Auschwitz-Birkenau, set up by Nazi Germany in occupied Poland during World War II as the main center of their "Final Solution," the genocide of European Jews.

Auschwitz was liberated on Jan. 27, 1945, by the advancing Soviet army whose stunned soldiers released 7,000 emaciated prisoners left behind as the Germans withdrew.

"The snow was falling like today, we were dressed in stripes and some of us had bare feet," Polish survivor Kazimierz Orlowski, 84, said. "These were horrible times."

Candles were lit along the snow-covered rail tracks used during the war to take Jews and others in cattle trains to the camp, where many were gassed to death on arrival.

A whistle, the sound of a stopping train and door being flung open were played at the start of the ceremony in Birkenau, the camp´s main extermination center, to symbolize the arrival of the Nazi victims.

Elderly survivors, many accompanied by younger relatives, and some wrapped in blankets to keep warm, walked slowly past the rusting wire fences under a dark gray sky and heavily falling snow toward a monument to the victims.

"I am not here to talk about what happened. My only aim is to light a candle for my mother, whose ashes are who knows where in this camp," said Jan Wojciech Topolewski, a former prisoner whose mother died in Auschwitz.

Next to the ruins of crematoria, huge flames were burning in memory of the victims.

"I want to say to all people around the world -- this should not happen again," said Anatoly Shapiro, the commander of the troops who first entered Auschwitz.

"I saw the faces of the people we liberated -- they went through hell," he told an earlier ceremony in the southern Polish city of Krakow, some 70 km (44 miles) from Auschwitz.

VICTIMS, PERPETRATORS AND LIBERATORS

Among the more than 30 heads of state attending the ceremonies were the presidents of Israel, Germany and Russia, representing the victims, the perpetrators and the liberators.

"The story of the camps reminds us that evil is real and must be called by its name and confronted," Vice President Dick Cheney said earlier.

"We are reminded that anti-Semitism may begin with words but rarely stops with words and the message of intolerance and hatred must be opposed before it turns into acts of horror."

The guilt many European nations still feel at either complicity or indifference during the Holocaust has prompted fresh vows of "never again" from their leaders.

But such assurances come against a background of resurging anti- Semitism in Europe, recent mass-killings in Africa and Bosnia and the fading memory of the horrors as the war-scarred generation passes away.

Jewish leaders urged Europeans not to erase the history of Auschwitz from their conscience and resist "new anti-Semitism," on the rise in response to the Israeli-Palestinian conflict.

"We fear anti-Semitism. We fear Holocaust denial, we fear a distorted approach by the youth of Europe," Israeli President Moshe Katsav said.

French President Jacques Chirac, the first French leader to acknowledge France´s complicity in the Holocaust, said the European Union would stand united to counter anti-Semitism.

Set up in 1940 by the occupying Nazis, Auschwitz was initially a labor camp for Polish prisoners but grew into a death factory for European Jews shipped there from around Europe and Russia. At its peak the camp could hold 400,000 people.

More than one million Jews were killed but Gypsies, Poles, Russians also died in the camp. Hundreds were subjected to medical experiments by Nazi doctors trying to prove theories of Aryan supremacy. (Additional reporting by Wojciech Zurawski, Ron Popeski and Natalia Reiter) (© Reuters 2005 01/27/05)