Former Federal Reserve Chairman Alan Greenspan said negative interest rates, if pursued for an extended period of time, will eventually distort saving and investment.

"I wouldn't say dangerous, but it is clearly not productive," Greenspan, who left the Fed in 2006 after almost 20 years at its helm, said Monday in an interview with Bloomberg Radio and Television. "The big argument about excessively low interest rates for a very long period of time is that it warps the investment pattern on real investments."

Central banks in the Eurozone, Switzerland, Sweden, Denmark, and Japan have all pushed some key interest rates negative in recent years in efforts to stimulate growth and inflation. Policy makers in the U.S. lifted their benchmark rate in December after leaving it near zero for seven years.