The increase came despite a steep drop in output, because companies laid off employees and cut hours worked at an even faster pace.
Higher productivity can raise living standards because workers that produce more can earn higher wages without forcing companies to raise prices.
Labor costs rose 3 percent, down from the government's previous measure of 3.3 percent. A rapid increase in labor costs could fuel inflation, but most economists aren't worried about rising prices, as the recession is keeping a lid on wage demands.
The reports come a day before the department is scheduled to release its unemployment report for May. Economists expect that report will show employers cut a net total of 520,000 jobs last month.
That's on top of 5.7 million jobs that have been lost since the recession began in December 2007.
The unemployment rate, meanwhile, will rise to 9.2 percent from 8.9 percent in April, analysts forecast.
Troubles in the automotive sector could cause unexpected fluctuations in the claims data. General Motors Corp. filed for bankruptcy protection Monday, joining Chrysler LLC, which filed April 30.
GM said earlier this week it will close nine factories and idle three others indefinitely as part of its restructuring. The closings, which will take place through the end of 2010, will cost 18,000 to 20,000 workers their jobs.
The company already planned to temporarily close 13 plants on a rolling basis this summer. Workers affected by the temporary shutdowns are eligible for unemployment benefits.
Chrysler, meanwhile, has temporarily idled all its U.S. factories after filing for bankruptcy protection, resulting in 27,000 layoffs. That decision caused claims to jump in the first week of May.
The shutdowns also could affect auto suppliers, which employ 3 million workers.
Initial claims are still below the peak for the current recession of 674,000 in late March. Many economists see the decline as a sign that layoffs outside the auto sector have peaked. But the unemployment insurance data remain significantly higher than a year ago, when initial claims were 370,000 and the total benefit rolls stood at 3 million.
Among the states, Illinois had the largest increase in claims, with 3,881, which it attributed to layoffs in the manufacturing and service industries. The next largest increases were in Iowa, South Carolina, Texas and Wisconsin. The state data lag initial claims by a week.
North Carolina had the largest drop in claims of 3,952, which it attributed to fewer layoffs in the construction, furniture and transportation industries. The next largest decreases were in Michigan, Ohio, Tennessee and Connecticut.
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