Two NYPD officers are under investigation after taunting they would "slap the shit" out of a man in an expletive-laden confrontation captured on video and posted to social media.

Video posted to Twitter on Wednesday night showed patrol officers pulled over on New York City's desolate streets threatening the man, who appears to be screaming in a state of distress, over the vehicle's loudspeaker.

"Shut the f**k up or I'll smack the s**t out of you. I'll slap the s**t out of you," the officers can be heard before they continue antagonizing the man, saying "Yeah, yeah, yeah, yeah".

Gage Kearns, 29, filmed the video after hearing the officers driving down the street saying "eat a fat one" to the man, who was making noise in a way that made him appear upset.

"It looked as though he could have been homeless, there has been a larger homeless presence in Hell's Kitchen since the pandemic, but I couldn't believe what I was hearing," Mr Kearns said.

"Law enforcement is supposed to be just and make sure the community is protected and that wasn't doing anything to better the situation."

Activist for the NYC Anti Violence project Eliel Cruz, who posted the video to Twitter, said the incident went on for some time near the corner of 49th and 8th in Hell's Kitchen as the officers told the man to "suck my dick".

"The response to this egregious harassment and purposeful escalation should be swift," he wrote.

The chief of the NYPD's transit bureau, Edward Delatorre, responded to Mr Cruz that he was "equally alarmed" by the video and that their internal investigators were also looking into the matter.

The NYPD confirmed it opened an internal investigation into the matter after the incident in Midtown Manhattan surfaced on social media.