Vigilantes bound a man to a lamppost and tied a placard labelling him a pervert around his chest in a so-called street punishment attack in west Belfast.
A group of residents gathered while the man was apprehended in scenes reminiscent of the tarring and feathering attacks meted out to those accused of criminality in the 1970s and 80s.
Pictures of the man – who was accused of exposing himself to children – were widely circulated on Twitter and Facebook.
The incident happened in the St James area of the Falls Road on Thursday evening.
Witnesses said a police helicopter hovered overhead during the fracas, before the man was taken away by officers.
Police confirmed they were investigating the incident. A spokesman said they had received no complaints regarding indecent exposure.
A PSNI spokesman said: "Police received a report shortly before 9pm that a man had been tied to a lamppost in the area. Police responded and released the man, who had sustained minor injuries.
"Police are aware that an image of this incident has been posted on a social media site."
The spokesman said it was for police, not members of the public, to apprehend those suspected of crimes.
"The PSNI is responsible for law enforcement and does not tolerate any type of vigilante activity," he said.
"Neighbourhood police officers are committed to working in partnership with local communities to address any issues or concerns and it is vital that anyone with information on any illegal activity contacts their neighbourhood police officers, their local police station or indeed a community representative who can pass the information to police so that the matter can be fully investigated by police officers."
STORY SO FAR
Vigilante groups used public humiliation as a form of punishment in Northern Ireland during the Troubles. Tarring and feathering was used in the 1970s and 1980s, and in the 1990s there were incidents of alleged drug dealers being tied to lampposts with placards listing what they were accused of.