An Illinois park is investigating after a woman accused one of its police officers of standing by while a man harassed her for wearing an "un-American" shirt bearing the Puerto Rican flag.

24-year-old Mia Irizarry was wearing a shirt when she rented out a section of the local park for her birthday party. A man then allegedly began harassing her repeatedly questioning her citizenship status.

That’s when Ms Irizarry began recording the incident on her phone and asking a police officer — who was just feet away — for help. In her video, the male officer does not appear to respond to her pleas, even at multiple points when the man begins walking towards her and raising his voice.

“You should not be wearing that in the United States of America,” the man says, walking into the space which Ms Irizarry rented for her party. ”Are you a citizen? Are you a United States citizen?”

“Officer, I'm renting, I paid for a permit for this area.. I do not feel comfortable with him here, is there anything you can do?” Ms Irizarry asks.

Other park visitors called the local police department, at which point a female officer took down a report on the incident and stopped the man from speaking to Ms Irizarry.

“You don't come here harassing people,” the officer said. ”People have just as much right to be here as you and when you're drunk, you don't belong here.”

The male officer on the scene during the incident has been placed on desk duty as an investigation into his response t the incident from mid-June is continuing, according to the Forest Preserves of Cook County.

“The intoxicated individual involved in the incident was arrested and charged with assault and disorderly conduct,” the organisation wrote in a series of tweets. ”All people are welcome in the Forest Preserves of Cook County and no one should feel unsafe while visiting our preserves.”

The video was shared this week by the news outlet NowThis, receiving over 23m views in under 24 hours. It’s just the latest in a trend of viral videos showcasing incidents of perceived racial profiling and hate.