Federal Reserve chairman Ben Bernanke said long-term unemployment was an American "national crisis" and urged the US government to take further action to combat it.
Mr Bernanke, who also said the government should provide more help to the battered housing industry, noted that about 45% of the unemployed had been out of work for at least six months.
"This is unheard of," he said in a question-and-answer session after a speech in Cleveland, Ohio.
"This has never happened in the post-war period in the United States. They are losing the skills they had, they are losing their connections, their attachment to the labour force.
"The unemployment situation we have, the job situation, is really a national crisis."
Mr Bernanke said the government needed to provide support to help the long-term unemployed retrain for jobs and find work and suggested that congress should take more responsibility.
Responding to a question, Mr Bernanke said long-term unemployment, budgetary discipline and housing policy were the three most important areas where congress could contribute to an economic recovery. "There are certainly some areas where other policymakers could contribute," he said.
His comments were his latest in a public effort to make congress act further to rejuvenate the economy. He suggested that the Fed could achieve only so much through policies that seek to lower long-term interest rates.
"The Federal Reserve has made enormous efforts to try to help this economy recover and stabilise" though its control of interest rates, or monetary policy, he said. Those policies had driven rates to record lows, he said.
"Monetary policy can do a lot, but monetary policy is not a panacea," he added.