Prince Albert of Monaco and Princess Charlene have visited the memorial of the former Nazi German death camp of Auschwitz-Birkenau and laid flowers at its Execution Wall.

The couple walked on Friday through the "Arbeit Macht Frei" (Work Makes you Free) gate into the Auschwitz camp and visited its crematorium and red-brick barracks that house inmates' belongings and hair. They wrote in the visitors' book that the memory of the atrocities will never be extinguished.

Prince Albert also visited the wooden barracks and memorial at nearby Birkenau, where Jews were brought to their death at the gas chamber or forced into hard work.

Some 1.5 million people, mostly Jews, were killed at the camp between 1940 and 1945.

The royals also visited Warsaw and Krakow on their four-day Polish visit.