WASHINGTON — More employers are expecting to hire in the third quarter, with gains in all industries and across the country, according to Manpower’s employment-outlook survey released Tuesday.

A seasonally adjusted net 12 percent of employers said they plan to add to their workforce in the third quarter, up 1 percentage point from both the second and third quarters of 2012.

“At a very slow pace, the labor market is improving and the intention to hire is improving as well,” said Jonas Prising, president of ManpowerGroup, a Milwaukee-based staffing services firm.

Manpower’s report paints a picture of a national labor market that is consistently adding jobs at a moderate pace.

Last week the U.S. Department of Labor reported that the U.S. economy gained 175,000 nonfarm jobs in May. Over the quarter ending in May, there was an average monthly gain of 155,000 nonfarm jobs, slightly higher than a monthly average of 147,000 additional jobs for the quarter ending in May 2012.

The Manpower report, based on interviews with more than 18,000 employers in the U.S., measures the percentage of firms planning to hire minus the percentage of those intending layoffs.

The share expecting to increase staff is at a four-year high.

“This is just a further manifestation of an increase in employers’ confidence in slow, measured, but steady growth, and they are adjusting their hiring intentions,” Prising said.