Two top Federal Reserve officials on Monday defended the central bank's most recent effort to boost growth, with one suggesting further steps may be justified.

The central bank last week, warning of significant downside risks to the economy, announced it would weight its $2.85 trillion portfolio more heavily with longer term securities in an effort to drive borrowing costs lower.

Fed Governor Sarah Raskin and St. Louis Federal Reserve Bank President James Bullard both defended that move as warranted given the nation's 9.1 percent unemployment rate, with Raskin hinting she would support more action.

Additional policy accommodation is warranted under present circumstances, Raskin said at an event sponsored by the University of Maryland's Smith School of Business.

She said aggressive Fed efforts to foster stronger growth and bring the jobless rate down have been muted by declines in home values and consumer reticence. The Fed's policies are completely appropriate to help spur more robust growth, she said.

The comments from Raskin and Bullard, who called the Fed's ultra-loose monetary policy appropriate, are the first direct remarks on monetary policy from Fed officials since the central bank launched its latest program on Wednesday.

While support for the Fed's accommodative stance is to be expected from Raskin, who is associated with the central bank's employment-focused doves, the endorsement of policy centrist Bullard indicates solid support for the latest monetary easing, despite the three dissents the decision drew.

The economy grew at under a 1 percent annual rate over the first half of the year, and forecasters think it is plodding along at a sub-2 percent pace now. Employment growth braked to a halt last month, raising recession fears.

Fears of a renewed downturn are growing around the world as well. Reports in Europe and China showed private sector business activity declined sharply this month as the euro zone debt crisis and a stalling U.S. recovery hit confidence.

Despite heightened risks, the Fed's decision to stay active in boosting growth is controversial and will get a full airing in speeches scheduled over the course of the week.

One of the officials who dissented against the step, Minneapolis Fed President Narayana Kocherlakota, is due to speak later on Monday, and the other two no voters are scheduled to make public comments in coming days.

Outside the Fed, Republican congressional leaders urged the Fed last week to stay on the sidelines, saying its aggressive actions may have done more harm than good by risking inflation.

Fed Governor Raskin challenged politicians to contribute to efforts to lowering the jobless rate. Both fiscal and monetary policymakers should be considering a wide array of approaches for fostering job creation, she said.

The Fed last week announced $400 billion in long-term bond purchases matched with sales of the same amount of short-term securities in a bid to push down longer-term interest rates. It also said it would resume buying mortgage-related debt in an effort to help depressed housing markets recover.

Even so, the Fed stopped short of outright third round of bond purchases. Bullard, speaking at a conference in New York, said that a fresh round of buying would be a potent tool, suggesting the Fed may yet resort to that measure although it would likely draw loud objections from critics who see it as setting the stage for a damaging surge in inflation.

The Fed cut benchmark short term rates to near zero almost three years ago and has bought $2.3 trillion in longer term assets to further stimulate economic activity.

Despite the three dissents last week, a core group believe the central bank should do what it can to prevent persistently high unemployment from slowing growth to the point the economy slides back into recession.

Fed officials are discussing measures including giving specific targets for unemployment and inflation that would reassure markets that the Fed won't quickly change the course of its ultra-loose policy.

Raskin said she would not support any policies that would permit inflation that is higher than what the Fed believes is optimal -- 2 percent or a bit less.

Raising inflation or raising inflation expectations ... is something I would be quite leery of, she said on Monday in response to questions after a speech to a University of Maryland event. Keeping inflationary expectations anchored is in my mind extremely important.

Bullard similarly said a higher target for inflation would not help achieve the Fed's goal of stronger growth.

(With additional reporting by Kristina Cooke in New York)

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