The US Federal Reserve chief Janet Yellen says there is no need at this point to change the central bank's near-zero interest rate policy.
She was responding to concerns the policy could be contributing to an investment bubble.
Yellen spoke on Wednesday in Washington at an event sponsored by the International Monetary Fund.
She said the primary focus for now should be attaining price stability and generating jobs, in order to redress concerns about financial stability.
Yellen said she will continue to be cautious of excessive risk-taking by investors.
But she said this should be handled primarily by government regulation and supervision.
In New York, the Dow Jones Industrial Average has been rising to record levels. And there are signs of overheating in the market for bonds of firms with low credit ratings.
Some market players say the Fed's continuing low-rate policy is fuelling these trends.
After her speech, the fed chief met with IMF head Christine Lagarde.
Officials at the IMF have been urging the Fed to ensure its policy changes do not cause instability in emerging economies.
Yellen said she will explain US monetary policy to reduce the effects on those economies.
Jul. 3, 2014 - Updated 00:54 UTC