Chairman Ben Bernanke is standing by the Federal Reserve's low-interest-rate policies, cautioning that any move to raise rates prematurely could derail a still-modest economic recovery.
Bernanke also sought to calm fears that super-low rates risk igniting inflation or rattling investors, during a speech late on Friday in San Francisco to an economic conference sponsored by the San Francisco Federal Reserve Bank.
The central bank's low-rate policies are intended to encourage borrowing and spending to boost the economy. Higher rates would make borrowing more expensive.
Bernanke said the Fed's policies mirror what other central banks around the world are doing.
"Long-term interest rates in the major industrial countries are low for a good reason: Inflation is low and stable and, given expectations of weak growth, expected real short rates are low," he said.
"Premature rate increases would carry a high risk of short-circuiting the recovery, possibly leading - ironically enough - to an even longer period of low long-term rates," he said.
His comments amplified testimony he gave to Congress this week.
Critics, including some Fed regional bank presidents, have expressed concerns that the Fed may be raising the risk of inflation through its purchases of Treasury bonds and mortgage-backed securities.
As he did in his appearance before House and Senate committees this week, Bernanke sought to provide reassurance that the central bank is closely monitoring developments in financial markets to guard against such risks.
He said 2010 financial regulatory overhaul has forced banks to boost the required capital on hand to cushion against losses. The Fed also conducts annual stress tests to make sure that the nation's largest financial institutions have sufficient resources to survive adverse economic conditions, he said.
"We pay special attention to developments at the largest, most complex financial firms, making use of information gathered in our supervision of the institutions," Bernanke said.
In December, the Fed set a goal of keeping its key short-term interest rate near zero until unemployment has fallen below 6.5 per cent. Unemployment in January stood at 7.9 per cent and many economists believe it will not drop below 6.5 per cent until late 2015 at the earliest.