The stone-and-metal memorial for Capt Witold Pilecki is located near the place where in September 1940 the clandestine army fighter let himself be caught by the occupying Nazi Germans.

It was a step towards becoming an inmate of Auschwitz, which the Germans operated in southern Poland.

Pilecki's son, Andrzej Pilecki, and daughter, Zofia Pilecka-Optulowicz, and other descendants joined hundreds of Warsaw residents and authorities at Saturday's ceremony.

Deputy Prime Minister Mateusz Morawiecki said Pilecki was twice victorious, first when he was ready to sacrifice his life for the defence of Poland and second when the memory of him and other resistance fighters survived the communist regime.

Pilecki wrote and smuggled out secret reports from Auschwitz to his superiors before fleeing under the cover of the night in April 1943. As a freedom fighter, he was caught by the Moscow-backed communist government imposed on Poland after the war, and after a year of brutal questioning and torture, was executed in May 1948.