The number of Americans filing new claims for unemployment benefits last week rose to its highest level since May, which could raise concerns about some weakness in the labor market.
Other data on Thursday showed nonfarm productivity contracted more sharply than previously thought in the fourth quarter as output failed to keep up with a jump in hours.
Initial claims for state unemployment benefits increased by 7,000 to a seasonally adjusted 320,000 for the week ended Feb. 28, the highest reading since mid-May, the Labor Department said on Thursday.
The Labor Department said there were no special factors influencing the report.
"We suspect the pattern reflects the weather rather than fundamental deterioration. That said, we will, of course, be on watch for the possibility that the rise in the last two weeks marks a change in the trend," said Jim O'Sullivan, chief U.S. economist at High Frequency Economics in Valhalla, New York.
Claims have been choppy in recent weeks because of public holidays and a very snowy and cold February. Through the volatility, however, the underlying trend had remained consistent with a strengthening labor market.
Economists polled by Reuters had expected claims to fall to 295,000 last week.