WASHINGTON – The Federal Reserve's low interest-rate policies are giving key support to an economy still burdened by high unemployment, Chairman Ben Bernanke told Congress on Tuesday. Bernanke signaled that the Fed's efforts to keep borrowing costs low will continue.

In a statement, Bernanke acknowledged that the Fed's aggressive program to buy $85 billion a month in Treasurys and mortgage bonds to keep rates low could eventually ignite inflation or unsettle investors. Several Fed policymakers said at their most recent meeting that the Fed might have to scale back its bond purchases because of those risks.

But Bernanke, delivering the Fed's semiannual report to Congress, said the risks remained contained for now.