The sketches in coloured ink on yellowish paper date from 1941 and 1942, when the main sections of the complex were built by the Nazis in what is now southern Poland.

Discovered last year in a Berlin flat, they include floor plans, detailed cross-sections of buildings and maps.

One sketch shows plans for a 10 by 11 metre room labelled "Gaskammer" or gas chamber, while another displays a large hall named "L-Keller", which experts say is probably an abbreviation for "Leichenkeller" or corpse cellar.

Underneath the description is a note saying the cellar "can be extended".

One of the pages shows what experts believe are the initials of Heinrich Himmler, the top lieutenant of Adolf Hitler who was closely involved in the killing of millions of Jews.

"We believe the plans circulated in Berlin for a while and were in the possession of the secret police of the East German regime," said Ralf Georg Reuth, an author who has written about the Nazi period and works for Bild newspaper, which purchased the 29 sketches and published a story about them in November.

Experts have identified the person who made most of the sketches as a Polish Catholic prisoner at Auschwitz, who survived the war and was later found by the Red Cross, living in Venezuela, South America.

The exhibition is located at the Berlin headquarters of Axel Springer Verlag, which owns the Bild tabloid. It will later move to Hamburg and perhaps abroad, organisers said.

About one million Jews were killed by the Nazis before the "Final Solution" was formulated in late 1941 and later approved at the Wannsee Conference in January 1942.

The concentration camp at Auschwitz-Birkenau in Poland was the largest built by the Nazis and an estimated 1.1 million Jews were killed there.

Auschwitz I was set up in May 1940 in an old Polish army barracks. The first victims were gassed in September 1941. Auschwitz II, or Birkenau, opened in October 1941. Four large gas chambers were added to the camp in January 1942.