An off-duty police officer accused of putting his knee on a 12-year-old girl's neck to restrain her amid a lunchtime fight in the US state of Wisconsin, is under investigation, a media report said on Tuesday.

The surveillance footage released on March 19 by Kenosha Unified School District shows that officer Shawn Guetschow, who was working as a security guard at the school, intervening in a fight on March 4 by placing his knee on the girl's neck for half a minute to subdue her, Xinhua news agency quoted the NBC News report as saying.

Wisconsin police officer accused of kneeling on girl's neck: Report

Jerrel Perez, the girl's father, has called for criminal charges against Guetschow for using a type of restraint that was banned for Wisconsin law enforcement officers last year.

Perez said his daughter is in therapy and seeing a neurologist for her injuries.

Guetschow resigned from his security guard post with the school on Tuesday, but remains employed by the city police force, Kenosha Police Department tweeted.

In a similar incident which led to widespread protests against brutal killings in police custody, African-American man George Floyd died on May 25, 2020, after now-ousted police officer Derek Chauvin knelt on the victim's neck nine minutes and 29 seconds.