WASHINGTON — Federal Reserve Chairman Ben Bernanke says the U.S. job market remains weak despite three months of strong hiring and that the Federal Reserve’s existing policies will help boost growth.

Further job gains will likely require more robust consumer and business demand, Bernanke said this morning in a speech at the National Association for Business Economics spring conference in Arlington, Va.

Bernanke’s comments suggest the central bank is prepared to keep interest rates near zero unless the economy improves substantially.

While the job gains have led to some increase in consumer confidence and incomes, “we have not seen that in a persuasive way yet,” Bernanke said in response to a question. He said the Fed needed to “remain cautious” in deciding what its next moves should be.

Stocks rose sharply after Bernanke’s speech. The Dow Jones industrial average increased more than 100 points in the first hour of trading, and broader indexes also gained. Traders may have interpreted his tempered view of the job market as a sign the Fed could take further steps to boost the economy.