Federal Reserve staff conducted a wide survey but found no evidence so far that the U.S. central bank’s ultra-low interest rate policy has encouraged excessive risk-taking, the Fed said on Wednesday. But it will keep the issue under close watch.

Minutes of the Fed’s March 19-20 meeting noted Fed staff had investigated concerns voiced by some policymakers that near-zero rates might lead to excessive risk-taking as investors “reach for yield,” which could foster asset bubbles in certain markets.

“Low interest rates likely have supported gains in asset prices and encouraged the flow of credit to households and businesses, but these changes to date do not appear to have been accompanied by significant financial imbalances,” the minutes said.

The Fed voted at the March meeting to maintain bond purchases at a monthly pace of $85 billion, and to hold rates between zero and 0.25 percent at least until U.S. unemployment hit 6.5 percent, provided inflation stayed under 2.5 percent. The U.S. jobless rate in March was 7.6 percent.Federal Reserve Facade 1

Fed Chairman Ben Bernanke has repeatedly stressed that he takes the potential costs of bond purchases very seriously, in a hint that the bond buying program might get scaled back if its costs began to outweigh the perceived benefits.

The minutes underscored the Fed does not believe that to be the case yet. But the minutes did acknowledge that something might be going on, based on a wide survey of financial markets and institutions for signs of excess valuations, leverage or risk-taking, which could pose a wider risk to the system.

“Trends in a few specifics markets bore watching, and the staff will continue to monitor for signs of developments that could pose risks to financial stability,” the minutes said.

Policy hawks uncomfortable with the Fed’s extremely aggressive actions to spur the U.S. jobs market fear it could be laying the ground for a repeat of the next financial crisis.

Kansas City Fed President Esther George specifically warned last week that sharp rises in farmland prices as well as on high-yield bonds were reasons for caution when debating how long to maintain the Fed’s extraordinarily easy monetary policy.