WASHINGTON — The number of people seeking U.S. unemployment benefits rose 10,000 last week to a seasonally adjusted 379,000, the highest since March. The increase may reflect volatility around the Thanksgiving holidays.

The Labor Department said Thursday that the less volatile four-week average jumped 13,250 to 343,250, the second straight increase.

Benefit applications are a proxy for layoffs. Last month, they fell to nearly the lowest level in six years, as companies cut fewer jobs. But two weeks ago, they surged 64,000 to 369,000.

Economists dismissed that spike, saying it likely reflected a Thanksgiving holiday that fell later in the month. That can distort the government’s seasonal adjustments. But if the trend continues it would be a troubling sign of rising layoffs.

The number of people receiving benefits rose sharply – 4.4 million people in the week ended Nov. 30, the latest data available. That was 600,000 more than the previous week. Those figures aren’t adjusted for seasonal patterns.

Still, most other recent job market data has been positive and economists generally expect unemployment benefits applications will soon fall back.