Federal Reserve officials expressed considerable uncertainty before they took a nearly unanimous vote Aug. 10 to take a modest step to bolster the flagging recovery, according to the central bank's minutes of the meeting. The meeting, which lasted 5 hours and 35 minutes, longer than usual, ended with the Federal Open Market Committee, which sets monetary policy, voting 9-to-1 to use proceeds from the Fed's mortgage bonds to buy long-term Treasury securities. The action was largely technical -- it merely prevented the Fed's bond portfolio from shrinking -- but it was also strongly symbolic as it signaled a growing concern about slowing recovery and the risk of deflation. Since the Fed announced its action, the stock market has dipped. The minutes, released Tuesday, revealed that Fed officials were divided on how effective the purchase of long-term Treasuries would be, and on whether it would complicate an eventual return to normal monetary policy. While the committee closed ranks behind the Fed chairman, Ben S. Bernanke, who supported the move and whose views are generally decisive in setting policy, the minutes suggested that he would have to go even further to overcome his colleagues' reservations if the Fed were to resume buying huge quantities of government debt -- an action Bernanke has said he is prepared to take if the economy worsens significantly. The Fed used up its main policy tool by lowering short-term interest rates to nearly zero in late 2008. So it bought about $1.4 trillion in mortgage-linked securities and debts owed by entities like Fannie Mae and Freddie Mac, from January 2009 to March 2010, in an effort to ease credit and push down long-term rates. One consequence is that homeowners have been refinancing their loans and paying off their debts early. As a result, the nearly $2.1 trillion in domestic securities on the Fed's balance sheet was likely to shrink by nearly $400 billion by the end of 2011. To avoid an unintended 'passive tightening' of monetary policy, the committee agreed to reinvest proceeds from the Fed's holdings of mortgage bonds in long-dated government securities. A few committee members thought the effect of the decision 'would be quite small,' according to the minutes. (By one estimate, the decision lowered the yield on the benchmark 10-year Treasury note, which was 2.47 percent Tuesday, by 0.15 percentage points.) A few worried that the strategy 'could send an inappropriate signal to investors about the committee's readiness to resume large-scale asset purchases.' The minutes noted that one member argued that the decision 'was likely to complicate the eventual exit from the period of exceptionally accommodative monetary policy and could have adverse macroeconomic consequences.' While the minutes do not identify which members expressed what views, the sole dissenter was Thomas M. Hoenig, president of the Federal Reserve Bank of Kansas City. The minutes revealed a consensus that the economic outlook had softened and that inflation had fallen -- a phenomenon known as disinflation -- well below the implicit target of nearly 2 percent. Some members 'expressed a concern that in this context any further adverse shocks could have disproportionate effects, resulting in a significant slowing of growth going forward,' the minutes said. The economic sluggishness has made it ever more challenging for the Fed to meet its two-part legal mandate: maintaining price stability while promoting maximum employment. 'While no member saw an appreciable risk of deflation, some judged that the risk of further near-term disinflation had increased somewhat,' the minutes noted. 'More broadly, members generally saw both employment and inflation as likely to fall short of levels consistent with the dual mandate for longer than had been anticipated.' One argument against the risk of deflation is that long-run inflation expectations, which the Fed closely watches, have not fallen. But one committee member, the minutes reported, said that surveys showed that such expectations 'remained positive in Japan throughout that country's bout of deflation,' which began in the early 1990s. At an annual Fed policy symposium last weekend in Jackson Hole, Wyo., Bernanke explained the Aug. 10 decision and reiterated the Fed's commitment to intervene if necessary. But he emphasized the potential drawbacks to additional action and said he did not believe deflation was likely. Top economists attending the symposium were divided about what the Fed should do next. Raghuram G. Rajan, of the Booth School of Business at the University of Chicago, said he feared the Fed would repeat what it did after the last recession, in 2001. Fears about deflation in 2002-3 contributed to a decision to keep interest rates at very low levels until 2004. Some economists believe those low rates helped feed the housing bubble that began bursting in 2007. 'The pressure on the Fed to do the impossible -- to bring back the jobs -- is going to continue over the next few years, but it's very important that the Fed focus on what it can do, and move away from the emergency policy framework it put in place during the crisis,' he said in an interview. But James H. Stock, a Harvard professor, presented a paper arguing that inflation could fall even further by the middle of next year, given the enormous amount of unused capacity in the economy. 'One of the key lessons of monetary policy is that we need to be ready to deploy these tools if we see a further weakening of the economy,' Stock said in an interview, referring to the Fed's unconventional options, like asset purchases. 'And I happen to think you will see a further weakening.' 