Ota Sik, 84, a survivor of Nazi concentration camps who became the architect of economic liberalization during Czechoslovakia's ill-fated 1968 "Prague Spring," died Aug. 22 at a hospital in St. Gallen, Switzerland. No cause of death was reported.

Mr. Sik taught economics at the University of St. Gallen after Soviet troops ousted the reformist Czech government in 1968.

Czechoslovakia's communist government adopted Mr. Sik's economic ideas in 1965 to restart stagnant industrial growth. His "new economic model" called for limited reforms of the Soviet system, including less central planning and a freer market economy -- touted as a "third way" between communism and capitalism.

Mr. Sik, head of the economics institute at the Academy of Science, was appointed vice premier and economics minister in April 1968 as part of Premier Alexander Dubcek's reform campaign to create "socialism with a human face."

Warsaw Pact troops invaded on Aug. 20, 1968, to crush the effort, but Mr. Sik was on vacation in Yugoslavia and escaped the crackdown. That October, he moved to Switzerland, and his family joined him several years later.

Born in Pilsen, in the present-day Czech Republic, Mr. Sik studied art in Prague and painted in his spare time as an office worker before World War II.

After Nazi Germany occupied western Czechoslovakia in 1939, he was active in the resistance until he was arrested in 1940 and sent to the Mauthausen concentration camp in Austria. He studied politics and social sciences at Prague University after the war.

When Czechoslovakia's communist regime collapsed in 1989, President Vaclav Havel appointed Mr. Sik to a board of advisers made up of prominent Czechs living abroad. But Mr. Sik retained his left-wing views and criticized the country's shock economic liberalization, saying the immediate elimination of state subsidies would wreck many large communist enterprises.

"I cannot share a view which anticipates a quick rise in unemployment to hundreds of thousands or millions of people," Mr. Sik said in an interview in 1990.

He estimated in 1989, with some accuracy, that it would take at least 12 to 14 years for Czechoslovakia's economy to catch up with more prosperous Western nations. The two states created when Czechoslovakia split up in 1993 -- the Czech Republic and Slovakia -- finally joined the European Union in 2004.

Mr. Sik, who became a Swiss citizen in 1983, resumed painting after moving to Switzerland, exhibiting his pictures of colorful forms and shapes until late in life.