The number of U.S. people initially applying for unemployment aid last week went up again after falling to a three-and-a-half-year low in the previous week, a sign for fragile recovery in the labor market, the U.S. Labor Department reported Thursday.

The Labor Department said that the figure for seasonally adjusted initial claims for jobless benefits was 399,000 in the week ending Jan. 7, 24,000 more than the revised figure for the previous week.

The latest weekly figure, which came after three months of steady declines that brought applications of jobless benefits to the lowest level in more than three years, indicated that the U.S. job market is only recovering at an uneven pace.

Based on past data, the weekly jobless claims have to fall to 375,000 or below to signal a sustained drop in the unemployment rate.

Meanwhile, the four-week moving average, which helps to smooth out week-to-week volatility, edged up by 7,750 to 381,750.