Fed Governor Lael Brainard said on Friday that the Fed should wait until the U.S. economy strengthens before raising its interest rates further, adding that the interest rate decision was data dependent.

"Recognizing the data we have on hand for the second quarter is quite mixed and still limited, and there is important near-term uncertainty, there would appear to be an advantage to waiting until developments provide greater confidence," she said.

Brainard noted that the U.S. labour market slowed, while there were risks to the outlook from the slowdown in emerging economies and the referendum on Britain's membership in the European Union.

Brainard is a voting member of the Federal Open Market Committee.