Tucson’s largest school district will lose 10 percent of its state funding each month, Arizona’s school chief said on Friday, unless it alters its Mexican-American studies program to eliminate what he said was a “harmful, dispiriting message.”

The superintendent of public instruction, John Huppenthal, said the decision was made after an investigation by the Arizona Department of Education found that the Tucson Unified School District had violated state guidelines prohibiting public schools from teaching courses that single out particular ethnic groups.

“Unfortunately, in TUSD Mexican-American studies courses, a troubling, common theme arose time and time again in course and instructional materials, books and lesson plans: Latino minorities have been and continue to be oppressed by a Caucasian majority,” Huppenthal said in a statement. “This harmful, dispiriting message has no place in public education.”

Until the district changes its Mexican-American studies curriculum, the Arizona Department of Education will withhold 10 percent of the state’s monthly contribution to the Tucson district, the maximum allowed by law. If the district does not comply by the end of the fiscal year, in June, it stands to lose a total of $14.4 million. For the current school year, the district was supposed to receive $143.6 million from the state.

The state law, enacted in December 2010, dictates that no school can teach courses that promote resentment toward a race or class of people, or are designed primarily for pupils of a particular ethnic group. It also bars the teaching of “ethnic solidarity instead of the treatment of pupils as individuals.”

Huppenthal found the Tucson district in violation of the law last June, and an administrative judge, Lewis Kowal, upheld the finding at the end of December. Huppenthal waited until he reviewed the ruling to order the withholding of funds.

The TUSD has been in violation of the law since August, so the state will retroactively take funds. The district will not be required to pay the state any money, but approximately $4.9 million will be withheld from its February state funds, the total amount since August. Nearly $2 million will be withheld each month until the program is revised.

“Another $9.5 million is at stake if they don’t come into compliance by the end of the fiscal year,” said Ryan Ducharme, an Arizona Department of Education spokesman.

Kowal, a governor-appointed judge in the Arizona Office of Administrative Hearings, reviewed the case. The district can appeal to the judicial system.

“We feel they won’t take that avenue because he was very clear in his ruling,” Ducharme said. “As it stands, the law is correctly applied.”

The district said it had not yet decided whether to appeal. The TUSD Governing Board meets Jan. 10.

The TUSD voted 4-1 in favor of litigation after the state found in June that it had violated the law. But with the state’s latest ruling, and with one new member whose views are unknown, the board’s president, Mark Stegeman, said he was unsure what the board would decide.

Stegeman said it was unfortunate that the program was taking so much of the state’s attention.

“This program is currently serving fewer than 300 high school students of the 50,000 students in the district,” Stegeman said. “I think we’re all looking forward to the time when we can focus on the larger problems we have.”

Lisa Maria Garza contributed reporting.