By Jim Frank
Producer, BBC Radio 4's Law in Action
Opinion is divided on the extent to which dangerous dogs are used for criminal activity.
Some officials say it is on the increase but statistics are not kept and there no plans to change the way records are collated.
Pitbull-types are said to be among the dogs being used as "tools" of crime
A police authority, the RSPCA, a local authority, dog groups and the public all say it is a growing problem.
The types of animals used vary from Staffordshire Bull Terriers, Pitbull-types, and American bulldogs to so-called Canary dogs.
In April 2006, a man was attacked in west London with a meat cleaver over a row involving dogs not being on a lead.
They were snapping at his heels and after he protested to the owners they set them on him before hacking him savagely with the cleaver.
The police are treating the incident as attempted murder.
And last week, a man was sentenced to five years in prison after he set his dog on a police officer sent to a Manchester crime scene.
"I went into the address and was confronted by a man who was trying to intimidate me with a dog," says Sergeant Chris Allsop, of the Greater Manchester Police.
"The dog started jumping for my face, trying to bite me.
"I had to try and pin the dog down, putting my arms out, and pin it to the floor, and then also pin the male in the kitchen, whilst waiting for other officers to arrive and assist.
"I suffered cuts to both forearms, severe swelling, about the size of golf balls on each arm, several puncture wounds on my right arm on both sides, and I've got significant scarring on both forearms."
The RSPCA, the Metropolitan Police Authority, local authority dog warders and vets all think there is a growing problem with the criminal use of dangerous dogs.
Mark Callis, a senior dog control officer at Wandsworth Borough Council, says local rival gangs use them to settle scores.
"They just meet up with another gang, put these two dogs into a play pen or a tennis court or something like that and let them fight to see who wins and they decide who is the superior gang on who's got the better dog," he explains.
He also says the animals are being used to intimidate the public.
"The dog doesn't need to do anything.
"The fact that it's a Staffordshire bull terrier and there's a youth there threatening you and saying he's going to let the dog on you is enough to intimidate a lot of decent people.
"And there are cases where dogs are being used as weapons."
There are no official statistics to gauge the extent of the problem.
The Home Office say that there is no information recorded on when or if the animals are used as a tool of crime.
However, Mike Butcher, chief inspector of the RSPCA special operations unit, is certain that the criminal use of dogs is on the increase.
"We've noticed there's a very large increase in calls coming in from the public to say this is occurring.
"We work very closely with the police in London and elsewhere, and I'm aware of this rising trend as well from our police contacts.
"It's predominantly young people who walk around in groups, and I think the dog is a bit of a macho symbol, and the RSPCA's worry is that people get these dogs as a sexy image dog and they've got not idea what they've got hold of."
Superintendent Simon Ovens, of the Metropolitan Police Dangerous Dog's unit, denies there is a growing problem.
"It's certainly not reflected in the reported crime figures," he says.
With no change planned in the way crimes involving dogs are reported, the controversy over how many incidents there are looks set to continue.
Legal expert Trevor Cooper sits on a committee looking at potential changes to the Dangerous Dogs Act and possible dog Anti-social Behaviour Orders.
He says new dog control orders, which came into effect on 6 April, could help local authorities fight this problem.
New powers include a requirement for a dog to be kept on a lead in a specified place.
They can also be excluded from land altogether, and the number of dogs a person can have at any one time can be limited.
But to date, no local authority has implemented these new powers.
BBC Radio 4's Law in Action was broadcast on Tuesday 6 June at 1600 BST.