The number of U.S. workers filing new claims for jobless benefits increased last week, suggesting some modest slackening in labor markets. Jobless claims rose 11,000 to 321,000 on a seasonally adjusted basis in the week ended March 31, the Labor Department said Thursday. Claims for the week ended March 24 were revised to 310,000 from 308,000. The four-week moving average of new claims, which economists use to gauge underlying labor market trends, fell 1,500 to 315,750. Though up from previous weeks, the new claims data remain consistent with moderate expansion of U.S. payrolls. March nonfarm payrolls, due for release Friday, are expected to show a 150,000 increase, holding the unemployment rate steady at 4.5%. That would suggest ongoing support for consumer spending, which is being counted on almost exclusively for overall economic growth given headwinds in housing and manufacturing sectors. According to the Labor Department report Thursday, continuing claims for workers drawing unemployment benefits for more than a week fell by 25,000 to 2,492,000 in the week ended March 24, the latest week for which such data are available. That's the lowest level since the Jan. 27 week. There were 28 states and territories reporting a decrease in initial jobless claims for the week of March 24, while 24 reported an increase. Mississippi had the biggest decrease, 4,335. Michigan reported the biggest increase, 2,836, due to layoffs in the automobile industry.