Philadelphia Fed President Patrick Harker said in a speech on Tuesday that the Fed should delay its interest rate hike until inflation accelerated.

"It might prove prudent to wait until the inflation data are stronger before we undertake a second rate hike," he said.

Philadelphia Fed president that there were the downside risks to the inflation outlook.

Harker noted that the U.S. economy was strong.

"Overall, my view of the economy is upbeat. Our financial system is in good shape, our economic fundamentals are sound, our labour markets remain dynamic, and our income growth is solid. Consumer spending is also increasing at a solid pace," he said.

Harker is not a voting member of the Federal Open Market Committee (FOMC) this year.