An image from anti-fur demonstrations at London Fashion Week shows a police officer holding a vegan activist by the throat.
The incident took place at the weekend.
The campaigner in question is part of activist collective Surge.
Surge Co-founder Earthling Ed claims: "He is one of the most peaceful and compassionate people I have ever met.
"Today he was grabbed by the throat by a police officer merely because he was standing on an area of public land that the police didn’t want him to stand on.
"He was grabbed by the throat and choked even though he hadn’t committed any offences."
A Metropolitan Police spokesperson told PBN: "We are aware of an image posted on social media.
"We are in the process of establishing the circumstances of the incident."