NEW YORK (Reuters) - U.S. private employers added 154,000 jobs in September, below economists' expectations, a report by a payrolls processor showed on Wednesday.

Economists surveyed by Reuters had forecast the ADP National Employment Report would show a gain of 166,000 jobs, with estimates for the gain ranging from 140,000 to 181,000.

Private payroll gains in the month earlier were revised down to 175,000 from an originally reported 177,000 increase.

The report is jointly developed with Moody's Analytics.

The ADP figures come ahead of the U.S. Labor Department's more comprehensive non-farm payrolls report on Friday, which includes both public and private-sector employment.

Economists polled by Reuters are looking for U.S. private payroll employment to have grown by 170,000 jobs in September, up from a gain of 126,000 the month before. Total non-farm employment is expected to have risen by 175,000.

The unemployment rate is forecast to stay steady at the 4.9 percent recorded a month earlier.

(Editing by Meredith Mazzilli)