Federal Reserve Chairman Ben Bernanke and then-Treasury Department chief Henry Paulson pressured Bank of America Corp. to not discuss its increasingly troubled plan to buy Merrill Lynch & Co. -- a deal that later triggered a government bailout of BofA -- according to testimony by Kenneth Lewis, the bank's chief executive.

Mr. Lewis, testifying under oath before New York's attorney general in February, told prosecutors that he believed Messrs. Paulson and Bernanke were instructing him to keep silent about deepening financial...