U.S. small businesses stepped up hiring in August and more employers reported they could not find qualified workers for open positions, indicating the labor market was tightening.

The National Federation of Independent Business (NFIB) said on Thursday that small-business owners added a net 0.13 worker per company last month, up from 0.05 in July.

The NFIB survey of 656 small business owners throughout the country found that 18 percent reported increasing employment by an average of 3.0 workers per firm, up 6 points from July.

About eight percent said they had reduced payrolls by an average of 3.4 workers per firm, down 4 points from the prior month.

The survey was published ahead of Friday's release of the government's closely watched employment report for August.

According to a Reuters survey of economists, nonfarm payrolls likely increased by 220,000 last month, up from 215,00 in July. The unemployment rate is forecast slipping one-tenth of a percentage point to a near 7-1/2 year low of 5.2 percent.

The August jobs report will be released less than two weeks before the Federal Reserve's Sept. 16-17 policy-setting meeting. The chances of an interest rate hike at the meeting have been diminished by recent global financial markets volatility.

Still, the first increase in the Fed's short-term interest rate in nearly a decade remains a possibility.

Last month, 29 percent of small business owners reported they had job openings they could not fill, up 4 points, regaining the highest reading for this year.

"This strong a gain sets the stage for a decline in the unemployment rate and indicates that labor markets remain tight with owners having difficulty finding qualified workers," said NFIB chief economist William Dunkelberg.