MILWAUKEE (CBS 58) — The U.S. Department of Education has opened a civil rights investigation into Milwaukee Public Schools over whether race is being used as a factor in student discipline decisions.

In a letter dated Aug. 18 and addressed to MPS Superintendent Brenda Cassellius, the department's Office for Civil Rights said it is initiating a directed investigation of the district under Title VI of the Civil Rights Act of 1964.

OCR said it will investigate whether MPS is "using race as a factor when considering disciplinary actions against students."

The letter notes that opening the investigation is not evidence that MPS violated federal civil rights law. OCR said it will remain neutral while collecting and analyzing evidence to determine whether the district is complying with Title VI.

MPS said Wednesday that it had received the letter but had not been given details about what prompted the investigation.

"This morning, we received the letter from the U.S. Department of Education. The notice does not contain the basis or prompting for the investigation. Once we receive more detail, we would be able to respond appropriately," the district said in a statement to CBS 58.

The Department of Education announced the Milwaukee investigation Tuesday alongside a separate investigation into a school district in Fayetteville, Arkansas.

In its announcement, the department alleged Milwaukee education leaders had described some race-neutral school policies as reflecting systemic "whiteness," which federal officials said appeared to encourage school personnel to consider race in disciplinary practices.

However, the letter sent directly to MPS does not identify a specific incident, policy or complaint that prompted the investigation.

The investigation comes as the Department of Education issued new guidance directing schools to apply discipline policies without favoring or disfavoring students based on race.

The guidance follows the department's removal of disparate impact provisions from its regulations implementing Title VI. Those provisions allowed racial disparities in outcomes to be considered when determining whether a policy violated federal civil rights protections, even without an explicitly discriminatory policy or evidence of discriminatory intent.

"For too long, the left's pursuit of 'equity' has perversely required schools to discipline students differently, based on their race," Assistant Secretary for Civil Rights Kimberly Richey said in a statement announcing the new guidance.

According to the letter, OCR's Denver Regional Office will conduct the MPS investigation. Federal officials said they plan to contact the district within a week to arrange next steps, including requesting access to data and personnel.

Title VI prohibits discrimination based on race, color and national origin in programs or activities receiving federal financial assistance.