Despite being referred to as 'man's best friend', many dogs have an aggressive side.

And now a new study has pinpointed exactly which breeds are most likely to be aggressive towards other dogs.

Somewhat unsurprisingly, researchers from the University of Helsinki found that fighting dogs are the most aggressive.

This group includes American Bulldogs, American Pit Bull Terriers and American Staffordshire Terriers.

In contrast, Golden Retrievers, Labrador Retrievers and Scenthounds were found to be the least aggressive dogs.

In the study, the team set out to investigate the personality differences between dog breeds.

'The breed of the dog is the most important determinant underlying personality differences,' said Dr Milla Salonen, lead author of the study.

'All dogs are individuals, and all breeds have different traits, but the breeds differ in what kind of personality most dogs within each breed have.'

The team collected an enormous behavioural survey dataset containing information on 11,000 dogs across 300 different breeds.

These were then categorised into 52 groups.

The data revealed a strong link between breed and seven personality traits - insecurity, training focus, aggressiveness/dominance, energy, dog sociability, human sociability, and perseverance.

'Dogs scoring high in aggressiveness/dominance are aggressive to other dogs, dominant, and territorial,' Dr Salonen told MailOnline. 

'Whereas dogs scoring low are submissive, social with other dogs, and calming.'

Fighting dogs were revealed as the group with the highest levels of aggression.

This group includes American Bulldog, American Bully, American Pit Bull Terrier, American Staffordshire Terrier, Cane Corso, Dogo Argentino and Presa Canario.

Also at the top of the list were German Shepherds, Parson type terriers and Asian primitive dogs.

At the other end of the scale, Golden Retrievers, Labrador Retrievers, Scenthounds and Shetland Sheepdogs were found to be the least aggressive groups.

Aside from breed, several other factors were found to be linked to a dog's aggression.

Male dogs were found to be more aggressive than females, while dogs were most aggressive at age nine.

'Based on our research, personality traits are extremely complex and have astounding similarities between dogs, humans and other animals,' Dr Salonen added.