SAN FRANCISCO (Reuters) - U.S. central bankers are currently debating whether it should confine its controversial tool of bond buying to purely emergency situations or if it should turn to that tool more regularly, San Francisco Federal Reserve Bank President Mary Daly said on Friday.

“In the financial crisis, in the aftermath of that when we were trying to help the economy, we engaged in these quantitative easing policies, and an important question is, should those always be in the tool kit -- should you always have those at your ready -- or should you think about those are only tools you use when you really hit the zero lower bound and you have no other things you can do,” Daly told reporters after a talk at the Bay Area Council Economic Institute.

“You could imagine executing policy with your interest rate as your primary tool and the balance sheet as a secondary tool, but one that you would use more readily,” she added. “That’s not decided yet, but it’s part of what we are discussing now.”