The Independent Office for Police Conduct has begun an investigation into the actions of Lancashire Constabulary during the arrest of a 34 year-old man in Accrington on January 8.
Footage of the arrest, which was shared on social media, showed the man being restrained by a number of police officers.
The IOPC decided to independently investigate the actions of the officers involved after the watchdog received a voluntary referral from the force.
IOPC Regional Director Amanda Rowe said: “We understand why the images that were circulated caused considerable public concern.
“After the footage was shared on social media, a voluntary referral was made to us in relation to the conduct of two of the arresting officers.
“It is vitally important that the circumstances of the man’s arrest are subject to an independent investigation so we can fully understand what happened and impartially determine the facts.
“We have already begun to gather evidence, but would like to speak to anyone who may have witnessed the incident.”
The IOPC like to speak to anyone who witnessed the incident which took place at around 2pm on Lonsdale Street.
Witnesses can call 0800 029 4687, or email [email protected]