The Auschwitz-Birkenau Memorial and Museum in southern Poland, which preserves the site of the Nazi German death camp, said in a social media post that Czech was "prisoner No. 349 in Auschwitz."
He "died of exhaustion in the infirmary at Auschwitz" "on June 4 or 5, 1944," the museum said.
It noted that Czech was "one of the most important Polish skiers of the interwar period," a 24-time national champion, and a three-time Olympian.
The state-run Institute of National Remembrance (IPN) said that Czech was one of the greatest and "most versatile" Polish skiers of all time.
Before World War II, Czech represented Poland at three consecutive winter Olympics in various skiing events, including Alpine skiing, Nordic skiing and ski jumping. He competed without medaling at St. Moritz in 1928, Lake Placid in 1932, and Garmisch-Partenkirchen in 1936.
After the start of the war, Czech became a courier for the Polish underground from German-occupied Poland to the West. He was captured by the German Gestapo secret police in 1940.
Polish Prime Minister Mateusz Morawiecki has said that Czech was not only an outstanding athlete, but also an ardent patriot who was part of a resistance movement organised at Auschwitz by Polish war hero Witold Pilecki.
Source: PAP, IPN, Polish Radio