MANCHESTER, N.H. — New Hampshire’s largest school district must to do more to enroll minorities in college and career prep courses and should consider revising how it assigns students to strict academic levels, the U.S. Department of Education said Thursday.

The department’s Office for Civil Rights said a review of advanced placement courses offered by the Manchester School District found few black or Hispanic students in the classes.

For example, of 434 seats in the courses in 2010-11, only 17 went to black students and nine to Hispanic students, the review found. There were 381 black students and 596 Hispanic students enrolled that year. At two of the district’s three high schools, no Hispanic students were enrolled in the advanced courses. Before the department’s review was completed, the district voluntarily agreed to take steps to provide better access for minorities.