U.S. workers' productivity improved in the fourth quarter over the initially reported figure as labor costs rose faster than first assessed, the Labor Department reported Wednesday.

Nonfarm business productivity -- measuring the ouput per hour of workers -- increased by 0.9 percent from October through December, a revision from the previously estimated gain of 0.7 percent.

Unit labor costs were up by 2.8 percent on an annualized basis for the quarter. The initially reported increase was 1.2 percent.

In the third quarter of 2011, productivity increased by 1.8 percent and costs were up 3.9 percent, according to Wednesday's report.

The higher fourth-quarter productivity was due an upward revision in output, combined with a downward revision in hours worked, the Labor Department said.