US private employers added 158,000 jobs in March, the smallest gain in five months and falling short of economists' expectations, a report by a payrolls processor showed today.

Economists surveyed by Reuters had forecast the ADP National Employment Report would show a gain of 200,000 jobs. The report came in below the lowest estimates in a poll by Reuters and was the smallest gain since October.

Revisions to February's jobs gains were more positive, with the private payrolls figure raised to an increase of 237,000 from the previously reported 198,000, though January was revised down to 177,000 from 215,000.

The euro extended gains against the dollar immediately following the report, while Treasury bonds turned higher. US stock index futures saw little reaction around flat levels.

The ADP report, which is jointly developed with Moody's Analytics, comes ahead of the government's more comprehensive labour market report on Friday.

That report includes both public and private sector employment and is expected to show a gain in overall nonfarm payrolls of 200,000 last month, while the unemployment rate is seen holding steady at 7.7 per cent.

"It tilts the risk in that (weaker) direction for Friday's payroll numbers," Jim O'Sullivan, chief US economist at High Frequency Economics in Valhalla, New York, said of the ADP report.

"It doesn't mean the trend of job growth has suddenly slowed, but that's what people are worried about."

Economists often refer to the ADP report to fine-tune their expectations for the payrolls numbers, though it is not always accurate in predicting the outcome.

Reuters