There had been rumours. There had been aerial photographs. There had been the written testimony of a few escapees.

But it took liberation for the revelation of the shocking reality of the Nazis' concentration camps. Nowhere was this more true than when British and Canadian troops advanced on the camp at Bergen-Belsen, near Hanover, in April 1945. A truce with local German commanders enabled them to enter without a fight.

They were met with a stomach-churning vista of death, a torrid panorama of human suffering. The troops calculated there were 13,000 unburied corpses. A further 60,000 emaciated, diseased, spectral-like survivors stood and lay amongst them.

To mark the 80th anniversary of the liberation of Belsen, more than a thousand survivors and families attended commemoration events at the camp on Sunday. Row after row, they listened to people recount the horrors of the camp. They included Mala Tribich from London, 14 then, 94 now.

Belsen was, she says, "a place of skeletons, where the dead were piled up and the living shuffled around… There was death everywhere". Mala said she saw guards pulling the corpses along on blankets or by their limbs.

Another survivor, Esther Alice, who was aged 11 at the time, recalled the "horrible" memory of her mother dying in her arms in hut 221. The sun shone down on Sunday's spectacle, but Belsen still has the capacity to chill.