Federal Reserve Chair Janet Yellen said it is appropriate forU.S. central bankers to “proceed cautiously” in raising interestrates because the global economy presents heightened risks.

The speech to the Economic Club of New York made a strong casefor running the economy hot to push away from the zero boundary forthe Federal Open Market Committee's target rate.

“I consider it appropriate for the committee to proceedcautiously in adjusting policy,” Yellen said in the text ofprepared remarks Tuesday. “This caution is especially warrantedbecause, with the federal funds rate so low, the FOMC's ability touse conventional monetary policy to respond to economicdisturbances is asymmetric.”