(Reuters) -United Auto Workers President Shawn Fain is under investigation by an independent federal monitor over allegations of retaliation against other union leaders, according to a court filing on Monday.

Monitor Neil Barofsky opened an investigation in February to review allegations, including that the UAW secretary treasurer said she had faced retaliation for her refusal or reluctance to authorize certain expenditures for Fain's office, according to the filing. Barofsky also opened a probe into the secretary treasurer's actions. The UAW declined to comment.

Barofsky was appointed the federal monitor in 2021 as the UAW grappled with a corruption scandal that resulted in the federal convictions of several former leaders. Two former UAW presidents were sentenced to prison time as part of the probe.

The monitor expanded his investigation to also include allegations made by Fain against the leader of the union's Stellantis department. Fain took over the Stellantis department leader's duties at the end of May.

Fain alleged that the Stellantis department head's responsibilities were reassigned because of their "dereliction of duty" in connection with collective bargaining issues.

The monitor later received complaints that Fain's decision was an act of retaliation because the Stellantis head refused to engage in acts of financial misconduct to benefit others, according to the court filing.