The achievement gap that separates white and Asian students from black and Latino students has grown wider in Montgomery County in several measures of academic success, according to a report released Tuesday.

The 130-page report points to progress in five of 11 performance indicators in recent years. The school system improved on gaps in school readiness and high school graduation, for example. But disparities widened in advanced-level scores for state math exams in third, fifth and eighth grades. There were mixed results in two categories.

The report, by the County Council’s Office of Legislative Oversight, presents a complex portrait touching on race, disability and income in one of the nation’s higher-performing school systems — and Maryland’s largest. It comes as budget tensions ratchet up in Montgomery, with the achievement gap emerging as a flash point for some elected leaders concerned about groups of students being left behind even as the county spends about 50 percent of its operating budget on the school system.

County Council member Valerie Ervin (D-Eastern County), who chairs the council’s education committee, described the findings as alarming and said school leaders need to do more. Almost half of Montgomery students, about 48 percent, are African American or Latino.

“I could see if we were not putting resources into our school system,” Ervin said. “We are putting extraordinary resources into our school system.”

Ervin pointed to 2012 data on state math exams that showed fewer than 20 percent of black and Latino eighth-graders scored at advanced levels while more than 60 percent of white and Asian students did. “How is that acceptable?” she asked. “How are they magically going to all of the sudden be prepared?”

The release of the report came three days before County Executive Isiah Leggett (D) is due to unveil his proposed fiscal 2014 county budget. The Office of Legislative Oversight issued a similar analysis in 2008.

Achievement gaps are a national concern as educators seek to ensure fairness in public schools and work to help all students graduate high school prepared for careers or college.

In interviews, some council members said they are looking for more accountability on the issue and want specifics about what the school system is doing to close the gaps.

Other areas in which the divide grew wider included performance on Advanced Placement exams and SAT tests among graduates. For Latino students, the gap increased from 2010 to 2012 for the completion of Algebra 1 by eighth grade with a C or better.

“We still rank as one of the top spenders nationally in education, and then to lose ground is extremely concerning,” said Council Vice President Craig Rice (D-Upcounty), who called for more urgency. “It just boggles my mind that this can be so far below the radar.”

In a six-page letter that accompanied the report, Montgomery Superintendent Joshua P. Starr said he agrees with most of the analysis. He wrote that much of the $10 million the school system is seeking above mandatory funding levels in its budget proposal would help address achievement disparities, including 30 “focus” teachers to reduce class sizes in English and math at middle and high schools where students are struggling.

Starr said the funding would help improve math instruction and increase professional development and that 60 new jobs would serve students who are English-language learners. An additional 100 positions would increase services for special education students.

Montgomery has long sought to make strides on academic disparities, Starr said, adding that African American and Hispanic students from Montgomery “significantly outperform students in the state and nation” on AP and International Baccalaureate tests and SAT and ACT exams.

School Board President Christopher S. Barclay said the report’s findings “are the very things this board and superintendent have talked about over the last 18 months.” Montgomery, he said, has made progress on gaps in the early grades, “but we’ve got a lot more work to do in the middle grades to see that progress work its way into high school.”

In a general snapshot, the report concluded that achievement differences were smallest in measures of grade-level performance and grew larger in above-grade-level performance. Largest were gaps in “at-risk” measures, which include out-of-school suspensions and dropout rates.

Signs of improvement over time showed in gaps in school readiness, which narrowed for black and Latino students by 35 percent or more over five years. Gaps tightened for advanced reading proficiency on state tests among students in third and fifth grades but not in eighth grade.

The gap in graduation rates was reduced by 25 percent for black students over three years; 11 percent for Latino students; 8 percent for special education students; and 12 percent for students who qualify for free or reduced-cost meals.

Council President Nancy Navarro (D-Mid-County) said school leaders need to be more deliberate and sharpen their focus. The good news, she said, is that Montgomery’s school system is high-functioning and well funded, in a community that values education.

“If we can’t do this in Montgomery County, where can we do it?” Navarro said.