​An Air Force brigadier general has been demoted by one rank to colonel for mishandling a sexual abuse case involving a late staff sergeant who took her own life.

According to military sources on Saturday, the defense ministry last week passed the rare disciplinary measure on Air Force legal affairs officer Jeon Ik-soo and it was approved by President Yoon Suk Yeol on Tuesday.

The latest administrative measure has taken effect immediately, marking the demotion of a general-rank officer for the first time in more than 40 years.

Jeon is accused of mishandling the initial investigation into a sexual assault case of a noncommissioned officer, Lee Ye-ram, who experienced the abuse by her superior in March last year and committed suicide two months later.

A special counsel probe saw eight related figures, including Jeon, indicted in September this year. Based on the results, the defense ministry has been seeking its own disciplinary measure separate from the court trial.

Jeon can appeal the demotion within 30 days but if it's not accepted, he is likely to retire as scheduled next month with the title of colonel.