Boston Fed President Eric Rosengren said on Monday that if there is a significant improvement in the U.S. economy, the Fed should start raising its interest rate.

"If we see continued gradual improvement in the U.S. economy, it will be appropriate to gradually increase short-term rates," he said.

Rosengren hinted the possible interest rate hike in December.

"I would highlight that the data received recently have been positive, reflecting real improvement for the economy," Boston Fed president noted.

He added that December "could be an appropriate time for raising rates, as long as the economy continues to improve as expected".