The vast majority of property stolen from Europe's Jews by the Nazis and their collaborators has never been returned, despite highly publicized restitution efforts over the past decade, according to a new study.

The study, details of which were given to The Associated Press on Friday, shows that affected Jews and their heirs have received just a fifth of the wealth that was stolen from them during World War II and the Holocaust.

Property that is today worth between $115 billion and $175 billion is still missing, according to the study, compiled by the economist Sidney Zabludoff, a former CIA and U.S. Treasury official.

The study is to appear in the April issue of the Jewish Political Studies Review, a journal published by the Jerusalem Center for Public Affairs, an Israeli think tank.

Zabludoff's research showed that before the war, Jews owned property in Europe that was worth between $10 billion and $15 billion at the time.

Most of it is still missing, he writes in a summary of the report, despite "numerous clear and explicit international agreements and country promises made during World War II and immediately thereafter."

The reason for the "meager" results, Zabludoff writes, was "the failure to make a unique, comprehensive, and timely effort" to restore property to survivors or heirs of Holocaust victims.

Most of the assets restored to survivors and Jewish organizations was returned by European governments in the years immediately following the war, and more recent efforts have been far less successful. Zabludoff found that despite a major push for compensation mounted by Jewish groups such as the Conference on Jewish Material Claims Against Germany beginning in the 1990s, those late efforts resulted in the return of only 3 percent of the missing wealth.

Some of the unreturned property was destroyed in the fighting or liquidated by the Germans, while some is still being held by European governments or individuals, said Manfred Gerstenfeld, an editor of the journal.

"If one looks at how the Europeans behaved towards the greatest group of victims of the Second World War, they behaved fairly immorally," Gerstenfeld said.