Plosser also told reporters on the sidelines of the annual meeting of the American Economic Association that he hoped the U.S. central bank would stop buying bonds if the jobless rate indeed fell at this pace, which would bring the level of unemployment close to the Fed's threshold of 6.5 percent.

"Hopefully, if you're getting that close, you will have stopped asset purchases before you get to 6.5 (percent). Otherwise you have really got another problem on your hands," he said. Data released earlier on Friday showed the U.S. unemployment rate held steady at 7.8 percent in December.

(Reporting By Alister Bull; Editing by Chizu Nomiyama)