Minneapolis Federal Reserve Bank President Narayana Kocherlakota said Thursday that the U.S. central bank can do more to help Americans struggling with unemployment or under-employment.

High levels of part-time workers who say what they really want is full-time work shows "we are still below maximum employment: there's more we can do," Kocherlakota said. "Both inflation and employment being low represents an opportunity for us at the Federal Reserve to be doing more to help people."

Speaking in Billings, Montana, Kocherlakota repeated his view that rate hikes at any time in 2015 would be "inappropriate." He was not asked about, and did not address, rising doubts in financial markets over U.S. economic growth that have pushed out expectations of the Fed's first rate increase to late 2015.