A video is circulating online showing a police officer fighting off a man who sunk his teeth into his leg in an attack in Sheffield city centre.
South Yorkshire Police said the incident is another example of the shocking level of violence faced by police officers on the frontline.
It comes just days after an officer was left needing reconstructive surgery to his ear after an attack in Barnsley and after another bobby was left unconscious after he was throttled in Rotherham.
In the online video filmed in Cumberland Street, in Sheffield city centre last week, an officer was captured repeatedly striking a man around the head in a bid to get him to release his grip on his leg.
The footage was viewed by South Yorkshire Police's professional standards unit and the officer was deemed to have used 'reasonable force' to protect himself from his attacker, who had clamped his jaws around his leg.
The officer is not to face any action.
It was filmed by a passer-by who spotted two officers trying to restrain a man on the ground.
Neil Bowles, chairman of the South Yorkshire branch of the Police Federation, which represents rank and file officer, said officers in South Yorkshire are facing an increasing amount of violence on the frontline.
He said weapons are used against them and they are regularly kicked, punched and spat at.
"Generally we are noticing an increase of violence towards officers - from biting to punches, kicks, spitting and weapons," he said.
"Driving offenders are also ramming police cars, obviously with intent to prevent the car pursuing them, but reckless to the possibility of injuring officers inside.
"More often than not the offenders are so intoxicated on drink or drugs. They are beyond reasoning and appear immune to pain themselves.
"The rise in violence against the police is worrying of course to individual officers and their families. We leave home every day not knowing for sure when, of if, we will return and in what state.
"It's sapping morale and diminishing the service to the public if we are constantly thinking about how to stay safe. That is just for the day-to-day policing in the county, before one thinks that police officers are a target for terrorists just as much as the armed services."
Last week a police officer was left needing surgery after an attack in Barnsley.
He was carrying out routine inquiries into the theft of a vehicle when he was attacked at a house in Woodhead Drive, Blacker Hill.
The officer suffered a serious injury to his ear, which required reconstructive surgery.
Barnsley District Commander, Chief Superintendent Tim Innes, said the officer had suffered a 'shocking and appalling injury' and said the attack highlights the 'dangers' faced by officers on a 'daily basis'.
In another incident last month a police officer was left unconscious after he was throttled by a man in Farquhar Road, Maltby, Rotherham.
Suspects have been charged over both attacks.
Temporary Deputy Chief Constable, Rachel Barber, said: “Police officers respond to a vast number of calls on a daily basis, never knowing what they will be confronted with when they arrive at an incident.
“Officers are often faced with extremely dangerous and violent situations and they risk their own safety to ensure the public of South Yorkshire remain safe.
“I am proud to work alongside such dedicated and committed individuals who make the decision every day to place themselves in harm’s way, in order to serve and protect our local communities.”