Leaders of the largest American center for the study of Nazi mass murders of Jews today demanded the resignation of a leading West German banker and former wartime German financier from a new board that is advising the Roman Catholic Church on its finances.

Rabbi Marvin Hier, dean and founder of the Simon Wiesenthal Center, said Herman J. Abs, 81, honorary president of West Germany's Deutschebank, expropriated Jewish property for his personal use, helped finance the activities of Adolf Hitler's Nazi Party and may have been involved in the construction of a huge rubber plant that used slave labor at the Auschwitz concentration camp.

Hier told a news conference at the center here that exhaustive research by the center and independent authors showed Abs to be "a key official in the Nazi war machine" who "does not have the moral credentials to represent a spiritual institution such as the Vatican."

The Vatican recently announced the appointment of Abs, who is Catholic, to a permanent advisory board to the Institute for Religious Works, the Vatican bank, which is accused of being part of an Italian financial scandal.

Hier said center officials informed the Vatican and the Vatican's apostolic delegate in Washington of their findings more than a week ago. A center spokesman said later that Jorge Mejia, a Vatican official in charge of relations with Jews, told center officials today that he will meet with the Vatican secretary of state, Cardinal Agostino Casaroli, Thursday on the Abs matter.

Abs served as chairman of the executive board of the Deutschebank in Berlin from 1940 to 1945. Although never a member of the Nazi Party, he has been a partner in a banking house that served Hitler and other Nazi leaders even before World War II.

Hier said a report of the U.S. military government in Germany after the war recommended Abs be indicted for war crimes, but the recommendation was not carried out.

Charles Higham, a writer whose recently published book "Trading with the Enemy" deals in part with Abs, said at the news conference that Abs was one of a number of German officials the victorious Allied governments "considered essential to the reconstitution of the West German economy." Higham is the author of "Errol Flynn: The Untold Story," which alleges close ties between the actor and several Nazi leaders.

Hier said the most serious charge against Abs in his view concerned Abs' job as his bank's wartime representative on the supervisory board of I.G. Farben, the powerful German chemical and industrial conglomerate. I.G. Farben invested $250 million in a rubber plant at Auschwitz and the supervisory board discussed at two meetings "increased usage of slave labor," Hier said.

Hier said Texas Christian University researcher William B. Smith found records indicating that of 300,000 people who "passed through" the rubber plant, "about 25,000 were recorded as having been worked to death." Hier said that in an interview Abs later denied knowing about his bank's support of the Auschwitz plant and said he would have resigned if he had known.