TRENTON — New Jersey’s unemployment rate was 9.9 percent in August, a disappointing showing the governor’s office sought to blame on the way the federal government measures joblessness.

The state unemployment rate is preliminary and subject to revision. But the near double-digit joblessness at rates not seen in 35 years comes even as 5,300 jobs were added last month and job increases were reported in 10 of the last 12 months.

Charles Steindel, the Treasury’s chief economist, said the jobless rate is at odds with signs of economic recovery seen in the state. He said the household employment survey the federal Bureau of Labor Statistics uses to determine the unemployment rate is less reliable than a payroll survey of employers. The payroll survey showed a gain of 50,000 jobs over the past year while the household survey showed New Jersey losing 47,500 jobs during the period, he said.

“These are two totally divergent figures, the latter of which simply does not match other metrics of growth in the state,” Kevin Roberts, a spokesman for Gov. Chris Christie, said in a statement.

Patrick O’Keefe, director of economic research at J.H. Cohn, said both federal surveys provide equally reliable snapshots of unemployment, and the latest report shows continued sub-par performance for New Jersey’s job market.

New Jersey’s jobless rate has been above 9 percent for 39 months in a row, or more than three years. Christie, 50, took office in January 2010. August’s rate was essentially unchanged from the 9.8 percent the month before.

The state gained 3,500 public-sector and 1,800 private-sector jobs for the month, but some of those were temporary workers.

Senate President Stephen Sweeney, D-Salem, Gloucester, Cumberland, said the continued high unemployment rate is alarming and shows Christie is abandoning his responsibility to the citizens of the state.

“Every month we have to hear the same bad news, followed by the same inevitable spin from this administration trying to hide why it is so completely inept at getting people back to work,” Sweeney said.

Steindel said the administration used employer survey data to make its budget calculations, so it saw no reason to revise its revenue projections for the fiscal year that began July 1. The budget the Democrat-led Legislature adopted and the governor signed relies on 7.2 percent revenue growth through next June 30. Revenues were

4.9 percent below expectations for the first two months of the fiscal year.

New Jersey’s current jobless rate also does not count 14,700 people who left the labor market in August, many as discouraged job-seekers. If those people were still part of the labor pool, the state’s unemployment rate would be 10.3 percent, O’Keefe said.

Only California, Nevada and Rhode Island have unemployment rates above 10 percent.