Greenspan: Additional stimulus not needed

"The problem with fiscal policy is that it is very difficult to implement in a timely manner," Greenspan told the House financial services committee.

Greenspan said last year's tax cuts did show up as increased expenditures in July and August, but turned out to be effective.

The Fed also expressed confidence that the economy was emerging from recession but warned the recovery was likely to be moderate, raising hopes that the U.S. is in for a period of stable interest rates.

Economists took the influential Fed chief's words as a clear signal that interest rates would probably remain on hold while the U.S. central bank assesses the developing recovery.