The Federal Reserve faces a high bar for further monetary stimulus in the absence of deflation risks, but could maintain rock-bottom borrowing costs for a long time, a top central bank official said on Monday.

Dennis Lockhart, president of the Atlanta Fed, told Fox Business Network in an interview that the U.S. central bank's policy was already supporting the economic recovery, despite recent weakness in the labor market.

What the Fed can do is to sustain its current policy until it's clear that we are seeing really much stronger growth and we're seeing progress in bringing unemployment down, Lockhart said.

Asked about the Fed's pledge to keep interest rates at very lows levels for an extended period, he said it could translate into much longer than just a couple of policy meetings. Fed Chairman Ben Bernanke has argued the phrase meant at least two or three meetings but potentially longer.

The chairman said it's at least two or three meetings and it could go much longer, Lockhart said.

Some analysts have been speculating that, given the opposition to the Fed's second round of bond purchases that was completed the end of June, the central bank could provide further support to a still-ailing recovery by beefing up its verbal promise to very low rates.

Policy makers could potentially do so by promising to keep the Fed's bloated balance sheet steady for a certain period of time.

Still, Lockhart said a firmer inflation backdrop had shifted the Fed's calculus about the possible benefits and risks of further monetary accommodation.

The conditions we are facing now are not the conditions we faced last November when (the policy) was implemented, he said. At that time we were looking at the potential for deflation in the economy, he said, according to a transcript of the interview provided by the network.

Under the Fed's second round of quantitative easing, it purchased $600 billion of bonds.

Renewed weakness in the U.S. economy has sparked some speculation that the Fed could embark on a third round of quantitative easing, or QE3.

But Lockhart said that recent softness was due in part to temporary factors that should dissipate as the year progresses.

I am still predicting we will have a much stronger second half and a stronger beginning to 2012. Clearly the first half of the year is disappointing, Lockhart said.

He added that Congress should be careful in its efforts to rein in the budget to not cut spending too quickly and endanger an already-fragile recovery.

The U.S. economy grew just 1.9 percent in the first three months of the year, and the second quarter does not appear to have fared much better. U.S. unemployment climbed in June to 9.2 percent.

Ben Bernanke Inflation Quantitative easing