The U.S. Federal Reserve must avoid being locked into calendar-based policy commitments and instead ensure its forward guidance is flexible enough to allow it to respond to changing conditions, a top Fed official said in Hong Kong on Friday.

Dallas Federal Reserve Bank President Richard Fisher said he worried that predictable commitments were unsound policy as they could lead to false complacency and market instability.

"I question if it is sound policy to remove all uncertainty or volatility from the market," Fisher, a voting member of the Federal Open Market Committee (FOMC), said in a speech at the Asia Society in Hong Kong.

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The market's sensitivity to the Fed's timing forecasts was in full view last month. Stock, bond, and currency markets were hit hard by comments from Fed Chair Janet Yellen that an interest rate hike could follow around six months after the central bank ends its bond-buying stimulus, earlier than investors had expected.