Harsh words from the Oracle of Omaha. Berkshire Hathaway founder Warren Buffett called the ethically dubious stock purchases of his former top aid David Sokol “inexplicable and inexcusable,” though he took some responsibility himself for the controversy. Speaking in front of tens of thousands of Berkshire shareholders, Buffett said Sokol violated Berkshire's insider-trading rules and code of ethics when he bought shares of chemical maker Lubrizol after recommending that Berkshire buy it. But Buffett also said he had erred in not pressing Sokol for details when he mentioned he owned shares in the company. "I obviously made a big mistake not saying, 'Well, when did you buy it?'" Buffett said. The criticism and admission of guilt are Buffett's first public comments on the topic since he shocked the business world a month ago with a statement disclosing Sokol's resignation and purchases of Lubrizol. Sokol didn't wait long to fire back, releasing a statement Saturday through his lawyer calling Buffett's comments a "flip flop and resort to transparent scapegoatism." "David Sokol is deeply saddened that Mr. Buffett, whom he considered a friend and mentor, would disparage him as he has done today," said Sokol's lawyer.