The number of newly laid-off workers filing applications for unemployment benefits unexpectedly surged last week after having fallen sharply in the previous week.
The gain dampened hopes about how quickly the labor market may improve this year.
The Labor Department said Thursday that first-time claims for unemployment benefits rose by 31,000 to a seasonally adjusted 473,000. Analysts expected a small decline.
The increase followed a drop of 41,000 in the previous week which had raised hopes that the labor market, which has lost 8.4 million jobs since the recession began in December 2007, could be improving.