US private sector economic activity growth slowed slightly in December, with the services sector reading also edging lower, an industry report has shown.

Financial data firm Markit said its composite Purchasing Managers Index measured 56.1 in December, down slightly from the 56.2 posted last month.

A reading above 50 signals expansion in economic activity.

Last month's services sector PMI, also reported by Markit today, dipped to 55.7 from 55.9 last month, and was lower than the flash reading of 56.

Despite the slight dip in the main index readings, the pace of growth in hiring advanced for both the US services sector and the total private sector. 

The composite employment gauge rose to 55 from 52.4 last month, while the read on services employment rose to 55.2 from 52.4 in November, which was the lowest since March.

"The US economy appears to have ended 2013 on a strong note, especially in relation to hiring," Markit said.

The improvement in the rate of job creation sets the scene for another upbeat non-farm payroll report for December, it added.

The December non-farm payroll report is scheduled for release on Friday, and a Reuters survey of economists shows an expectation for 197,000 jobs created in the month.

Meanwhile, new orders for US factory goods rebounded in November, adding to signs of strong momentum in the economy in late 2013.

The Commerce Department said that new orders for manufactured goods increased 1.8%. October's orders were revised to show a 0.5% drop instead of the previously reported 0.9% fall.

Economists polled by Reuters had forecast new orders received by factories rising 1.8%.