Federal Reserve Chair Janet Yellen says the extraordinary measures the central bank has used to boost the economy are still needed.

Yellen's remarks are a signal that even after the Fed phases out its monthly bond purchases later this year, it will keep a key short-term interest rate at a record low for some time.

In her first major speech since taking over the Fed's leadership in February, Yellen continually describes the U.S. job market as being less than healthy despite some improvement. She says the difficulty many people are still having finding full-time work shows that low rates are still needed to encourage borrowing and spending.

Yellen says she thinks this view is widely shared by her Fed colleagues.