Small businesses created the most jobs in March in about a year, a survey showed, bolstering expectations of a fourth straight month of solid gains in nonfarm employment.

The National Federation of Independent Business said its survey of 757 small businesses found that the average number of workers per firm increased by 0.2 workers — the highest since January and February 2011 — after being flat in February.

The survey was published ahead of the release of the government's more comprehensive nonfarm payroll count on Friday. Nonfarm employment likely increased 203,000 in March, according to a Reuters poll, after rising 227,000 in February.

That would mark the longest stretch of payrolls increases topping 200,000 since 1999. The unemployment rate is seen holding at a three-year low of 8.3 percent.

"Overall, the March survey anticipates some strength in the job creation number with little change in the unemployment rate," said the NFIB in a statement.

However, prospects for the labor market dimmed somewhat, with 15 percent of respondents reporting unfilled job openings last month, down two points from February.

The share of businesses planning to add new workers fell for a fourth straight month.