Initial claims for US unemployment insurance benefits fell to their lowest level in nearly 42 years last week in another sign of tightening in the country's jobs market.

New jobless claims, a sign of the pace of layoffs, fell to 255,000 in the week through July 18, down 26,000 from the previous week, the Labor Department said Thursday.

The four-week moving average was pulled down to 278,500, compared with 303,000 a year ago.

While the new claims numbers added to other signs of a steady tightening of the workforce, economists have cautioned that jobs data in the US summer can be more volatile than in other periods.

Even so, the claims data supported the fall in the overall unemployment rate last month to 5.3 percent, the lowest level since April 2008.