WASHINGTON -- The number of people applying for unemployment benefits last week jumped to the highest level in three months, a sign that layoffs could be increasing.

The Labor Department says weekly applications rose by 11,000 to a seasonally adjusted 428,000.

The week included the Labor Day holiday. Applications typically drop during short work weeks. In this case, applications didn't drop as much as the department expected, so the seasonally adjusted value rose. A Labor spokesman says the total wasn't affected by Hurricane Irene.

Still, applications appear to be trending up. The four-week average, a less volatile measure, rose for the fourth straight week to 419,500.

Applications need to fall below 375,000 to indicate that hiring is increasing enough to lower the unemployment rate.