U.S. employers added just 51,000 jobs in September, far below market expectations, according to a government report on Friday that showed weakness in construction, manufacturing and retail.

The closely watched report on nonfarm payrolls from the Labor Department also showed the unemployment rate dipped to 4.6 percent from 4.7 percent in August. The 51,000-job gain in September was the weakest since October 2005, when only 37,000 jobs were added following Gulf Coast hurricanes.

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Wall Street economists had forecast nonfarm payrolls to expand by 125,000 workers last month, according to a Reuters poll last week.

August payrolls were revised up to a gain of 188,000 from an originally reported 128,000, while July was revised to a gain of 123,000 from 121,000.

But some traders and analysts had scaled back estimates after a weaker-than expected report on private payrolls from ADP on Wednesday. A Thursday afternoon auction of derivatives used by traders to hedge against surprises implied that September non-farm payrolls grew by about 116,210 jobs.

The report showed average hourly earnings rose by a lower-than-expected 0.2 percent, or 4 cents, last month, after an upwardly revised 0.2 percent gain in August. Analysts in the Reuters poll had expected a 0.3 percent rise in September.

In both September and August, average hourly earnings rose 4.0 percent from a year earlier, the highest since a 4.1 percent gain in March 2001. The August figure was revised up from a 3.9 percent year-on-year gain.

In addition, the length of the average workweek was unchanged at a seasonally adjusted 33.8 hours in September. The manufacturing workweek fell 0.2 hour to 41.1 hours.

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