The pilots strike and related layoffs at Northwest Airlines pushed up the number of first-time applications for unemployment benefits last week to a seven-week high.

Benefit claims totaled a seasonally adjusted 312,000, up from 304,000 the week before, the most since the week ending July 18, the Labor Department said Thursday. A department analyst attributed much of the increase to a large rise in Minnesota, the home state of Northwest, the nation's fourth-largest airline.Just two weeks earlier, claims had hit a four-month low of 299,000. For two consecutive weeks in late June and early July, they soared to 394,000, a result of the General Motors strikes.

A four-week moving average of claims, which smooths weekly fluctuations, rose to 304,500, up from 302,500 and the most in four weeks.

Despite global financial turmoil and weakness in American manufacturing, jobs remain plentiful. The nation's unemployment rate, at 4.5 percent in August, remained near a 28-year low.