Mr Fisher was speaking to the Japanese Bankers Association in Tokyo
A top US central banker has said that the unemployment rate in the country could jump above 10% this year.
Richard Fisher, a member of the Federal Reserve's interest-rate setting committee, said the central bank would use "every tool" to fix the economy.
The jobless rate rose to 8.5% in March, while 5.1 million jobs have been lost since the US recession began in December 2007.
A US unemployment rate of 10% would be the highest since June 1983.
The total number of unemployed people stood at 13.2 million in March, according to figures from the Department of Labor last week.
"Our economy faces a tough road. We are the central bank of the largest economy in the world, and we are duty bound to apply every tool we can to clean up the mess that our financial system," Mr Fisher said in Tokyo.
"I expect the unemployment rate to continue rising to a level that could surpass 10 percent by year-end," he added.
The Fed has cut rates to a record low and begun a policy of so-called quantitative easing, where it buys up government debt to push the cost of borrowing down and get businesses and consumers spending again.
The minutes of the Fed's March meeting will be released on Wednesday.