Black and Hispanic students in Montgomery County Public Schools are two to five times more likely to have been suspended in middle school and have the highest suspension rates in grades K-12, according to a new report detailing the achievement gap in the public school system.

Black students have the highest suspension rates in all grades, while Asian students have the lowest suspension rates overall.

A report released by the Office of Legislative Oversight on Tuesday details achievement gaps in MCPS, including measuring test scores and behavioral issues based on grade, race and other social issues such as special education needs. The report came after five years of research by the agency.

Overall, MCPS has reduced suspensions across the board, but numbers are still lopsided -- especially in middle school: Black students are five times more likely to be suspended, while Latino students are slightly more than two times more likely. In high school, those numbers drop slightly for black students -- down to just above four times more likely.

The report estimates that given the rate at which the suspension gap is narrowing, it could take another 36 years to eliminate the gap.

MCPS spokesman Dana Tofig said the school system is aware of the higher suspension rates for Montgomery's Hispanics and blacks, but he did not give any potential causes. He said the district has made progress in reducing suspension rates and is part of a work group focused on narrowing the gap between black and white student suspensions.

MCPS Superintendent Joshua Starr said in a letter with the report that some of the money he is seeking for fiscal 2014 aims to address some of the gaps. He intends to hire more middle and high school teachers to reduce math and English class sizes and restore some school psychologist and counselor positions to intervene when students are struggling.

Starr is asking for $3.8 million more than required under state law.

The report also shows that while MCPS is closing some gaps, particularly in reading proficiency, others are staying the same or widening. One of the largest gaps that is narrowing is reading proficiency by elementary students: Black and Latino students were 93 percent to 94 percent as likely as white students to demonstrate proficiency. But the gap is growing in eighth-grade Algebra I. In 2012, Latino and black eighth-graders were 50 to 56 percent as likely as their white peers to reach the performance goal set by the state in Algebra I.

Councilwoman Valerie Ervin, D-Silver Spring, said the achievement gap is bound to grow as MCPS sees a growing socioeconomic gap and more minority families.

"Unfortunately for many children in our school system, this gap is persistent and in some areas widening."