The number of U.S. workers filing new claims for jobless benefits unexpectedly fell last week, data on Thursday showed, while there was a rise in the number of those still on the benefit rolls after an initial week of aid.

Initial claims for state unemployment insurance declined to a lower-than-expected seasonally adjusted 545,000 in the week ended Sept 12 from 557,000 the week before, the Labor Department said. It was the lowest reading since early July.

Analysts polled by Reuters had forecast claims to rise to 555,000 last week from a previously reported count of 550,000.

A Labor Department official said there were no special factors affecting the numbers but noted the reference week included the Labor Day public holiday, and that unadjusted claims had fallen by more than the seasonal factors calculated by the department had predicted.

Continued claims of people still on jobless aid after an initial week of benefits increased by 129,000 to 6.230 million in the week ending Sept 5, the latest for which data is available. It was the largest one week gain since late June, when continued claims advanced by 180,000. Analysts had forecast continued claims would be 6.10 million.

The stubborn U.S. recession has destroyed millions of jobs since it began in December 2007 and economists expect the labor market will only slowly return to health even after growth decisively resumes.

In another key gauge of underlying labor market health, the 4-week moving average for new claims fell 8,750 to 563,000. This measure is closely watched because it is supposed to iron out weekly volatility.

(Reporting by Alister Bull, Editing by Chizu Nomiyama)