In 2004, Leibler confronted the leadership of the WJC over the issue of governance, financial transparency, and financial irregularities. The conflict between Leibler and WJC Chairman
Israel Singer revolved around the former's demand for an investigation into the transfer of $1.2 million from the organization's New York headquarters to a bank account in Geneva, and the subsequent transfer of the money by Singer into a trust account held by his friend. Leibler's calls for a comprehensive independent audit" brought him into conflict with Singer and Edgar Bronfman, the WJC's longtime "president, chief benefactor, and guiding force." In January 2005, Leibler resigned as WJC vice president, telling Haaretz that he "came to the conclusion that I cannot remain in an organization that requires me to give a stamp of approval to activities I deem inappropriate. Elan Steinberg also left the WJC amidst the controversy, while two other top officials were fired. Leibler wrote that his position had been "vindicated" but expressed "deep sadness" at the organization's disarray. In 2004, the
New York State Attorney General's Office began an investigation into the WJC. The AG's Office issued a report in 2006 that found "serious financial mismanagement" at WJC, including improper payments and loans to Singer. Under an agreement between the Attorney General's Office and WJC, Singer was barred from the organization's leadership roles and returned several loans and payments, and the WJC undertook reforms. The WJC subsequently filed a $6 million defamation suit against Leibler in the Israeli courts but withdrew the action less than six months later, and were ordered by the court to pay Leibler's legal expenses. A
PricewaterhouseCoopers audit in 2006 submitted by the WJC to the AG's Office found that the financial scandal was "significantly broader than has been publicly known," with some $3 million unaccounted for from 1994 to 2004. Leibler, described by the
Jewish Daily Forward as the "most persistent critic" of the WJC, said that these findings were not surprising. Leibler responded that "I stand by my view that those whose primary goal is to delegitimize and demonize the Jewish state should be marginalized from the mainstream Jewish community. That is not fascism. It is common sense. Leibler called for a full external investigation and disclosure of massive misappropriations of funds at the
Conference on Jewish Material Claims Against Germany (
Claims Conference), citing allegations of incompetence, impropriety and cover-ups, the absence of an independent review board, bureaucratization and a domination by a small clique, along with a failure to "prioritize the needs of survivors, who are now elderly and many of whom are living in dire poverty. In response Claims Conference
Julius Berman has accused Leibler of engaging "in irresponsible invective and baseless charges against an organization that for nearly 60 years has been the leading international advocate for the rights of Holocaust victims." In 2021, a biography on Leibler revealed that he had been operating in Australia as an Israeli intelligence asset from 1959. The biography detailed how he “acted unofficially under instructions from Avigur and Levanon, becoming a de facto operative for Israel on foreign affairs” ==Publications and writings==