主题：【编辑】美国经济周报十月（一） -- 南方有嘉木

The U.S. Federal Reserve must continue to prop up the economy for an extended period but can't do so indefinitely for fear of triggering an inflationary surge, Federal Reserve Chairman Ben Bernanke warned on Thursday.

The U.S. central bank has cut interest rates to near zero percent and pumped hundreds of billions of dollars into the financial system to counter the worst financial crisis since the Great Depression.

At a Fed conference, where he discussed the central bank's ballooning balance sheet, Bernanke made clear that policymakers were thinking how to terminate support as recovery sets in.

"Accommodative policies will likely be warranted for an extended period," Bernanke told participants at the conference held in the Fed's headquarters.

"At some point, however, as economic recovery takes hold, we will need to tighten monetary policy to prevent the emergence of an inflation problem down the road."

Bernanke sent a signal the Fed is gradually but steadily moving toward an exit from its supportive policies, even while evidence of the recovery has been mixed.