The Federal Reserve Bank of Boston President Eric Rosengren said on Tuesday that it does not matter when to hike the interest rate. He added that the interest rate hike will be gradual.

"While market attention has focused on the exact timing of potential rate rises, macroeconomic models of the economy overwhelmingly suggest little impact on the broader economic landscape from moving the timing of initial interest rate hikes forward or backward by a couple of months," he said.

The Federal Reserve Bank of Boston president noted that the employment target has been reached to start raising interest rates, but other targets such as inflation remain unclear.

Rosengren also said that the Fed should be cautious to start raising its interest rates due to the recent turbulences on the global markets.

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