San Francisco Fed President John Williams repeated on Thursday that he expects the Fed to raise its interest rates this year.

"I view the next appropriate step as gradually raising interest rates, most likely starting sometime later this year. Of course, that view is not immutable and will respond to economic developments over time," he said.

Williams added that the U.S. economy continued to strengthen.

Williams is a voting member of the monetary-policy-setting Federal Open Market Committee (FOMC) this year.