Shocking footage of a topless man being bitten by a police dog and dragged along the ground has emerged.
Police said it showed only a short part of an arrest following a fight on Saturday in Weston-super-Mare, Somerset.
The video, taken by a passer-by, shows the man lying on his front in the road with a police officer behind him and another in front holding the barking dog on a lead.
When the man starts to raise himself up, the dog lunges forward and the officer seems to lose control, getting dragged forward with the animal as it goes for his neck.
One police officer appears to attempt to pull the dog off but it does not release the man and he is dragged a short way along the road.
Onlookers can be heard in the background of the video shouting and whistling.
Louisa Rolfe, the Assistant Chief Constable of Avon and Somerset Police, said police had been called to the centre of the seaside resort in the early hours of Saturday to deal with a “large fight” involving several people.
She added: “During this incident, a man was bitten by a police dog as he was being arrested.
“We are aware of a YouTube clip and comments on social media channels about this incident.
“The incident has been referred to our Professional Standards Department for thorough investigation as we are keen to understand what happened.
“The YouTube clip is only a few seconds long and doesn’t show events before or after the arrest.”
Police did not give any information about the man’s condition and said it would “inappropriate” to comment further.
A comment from the force’s official YouTube account said they were looking into whether the use of the dog was “appropriate and necessary”.