Image copyright Anna Duthie Image caption Alex, seven, feels more secure with his dog Chester by his side, his mother said

Charities training support dogs for children with autism are calling for more regulation after figures revealed a quadrupling in requests for help.

The charities collectively recorded 3,795 inquiries in 2017 - compared with 946 in 2012.

They said demand for the free dogs meant longer waiting lists for desperate families who may instead turn to unaccredited paid-for alternatives.

The government said it wanted to create a UK standard.

Assistance dogs are trained to provide companionship and help children with autism remain safe and calm and in busy situations.

Charities Dogs For Good, which has centres in Banbury, Warrington and Bristol, and Sheffield-based Support Dogs, have recorded large increases in the number of requests for their services over the past six years.

Both train and supply dogs for children aged between three and 10 years old, with the aim of helping them have a more independent and fulfilled life despite their condition.

The National Autistic Society warned a badly-trained unregulated dog could make the situation worse for a child with autism.

'He feels he is in control'

Media playback is unsupported on your device Media caption Anna Duthie says assistance dog Chester helps her son Alex in stressful situations

Anna Duthie, from Leeds, said assistance dog Chester helped her son Alex in stressful situations.

She said her seven-year-old struggled to cope in busy places such as shopping centres and theme parks, but Chester, who came from Support Dogs, helped him to manage.

"He feels safe, he can hold on to Chester," she said.

"He feels he is in control of what's going on. It's very difficult to explain until you've really seen it.

"It makes everything a lot calmer, a lot easier, just having him there."

Mrs Duthie said she almost paid for a support dog that may not have been properly trained, but then an opportunity came up from Support Dogs.

She said: "If you get dogs going out into the community that aren't properly trained, that aren't behaving properly, that aren't trained to a standard where they can be in food places around children, it will given the whole industry a terrible reputation."

Chief executive of Support Dogs Rita Howson said: "The dogs have gone through months and months of training, intensive training, to make sure not only the welfare of the dog is not compromised but also to make sure that the dog is well-behaved, he's obedient and to make sure that he's right for that particular family.

"We see such a high demand for this particular service and the concern is that there are waiting lists, people will have to wait to get an autism assistance dog and they may go elsewhere and there are people out there who may be manipulating the situation.

"What I would like to see is a standard so that people don't fall into that trap that's happened before and to make sure that their dog's going to be trained to a high standard."

Because of the small number of trained dogs available, there are fears desperate parents are turning to non-accredited providers, which in some cases has led to families paying high prices for poorly-trained or untrained dogs.

The accredited charities provide trained dogs for free but other organisations can charge thousands of pounds.

Peter Gorbing, chair of Dogs for Good, said it could become a "tragedy for families" if dogs were found not to be fit for purpose.

"They need to meet really high standards and we think some kind of public access assessment should be the prerequisite for any dog that's going to be called an assistance dog," he said.

What is an autism assistance dog?

Image copyright Anna Duthie Image caption Providers of assistance dogs can voluntarily sign up to a national accredited umbrella body

Dogs are trained to provide safety for people with autism and reduce stress in social environments.

Autism is a lifelong developmental disability that affects how a person communicates with and relates to other people, and how they experience the world around them.

The assistance dogs are trained to provide safety and companionship, helping children remain calm and focused in busy places.

Dogs For Good said it trained about 10 dogs a year, providing ongoing support to the families who received them. As soon as a space becomes available, those interested go through an interview process to make sure they are suitable and if so, can wait up to 12 months for a dog.

Providers of assistance dogs can voluntarily sign up to a national accredited umbrella body - Assistance Dogs UK or Assistance Dogs International.

Carol Povey, the director of the Centre for Autism at the National Autistic Society, said: "It is really important that dogs are properly trained if they are working with autistic children, because if they weren't the dog could actually make the autism more difficult, it could cause more stress in the family.

"It is key that the dog is consistent, calm, and the child understands how the dog is going to behave at all times.

"In the past there have been occasions where unregulated dogs were matched to families with an autistic child and it caused a great deal of upset because the dogs weren't properly trained."

The Irish company Service Dogs Europe was investigated after families complained their dogs were untrained. The company shut down in 2015, leaving many unhappy customers out of pocket.

A Department for Work and Pensions spokeswoman said: "We value the work of assistance dogs charities in the UK, and we're encouraging the assistance dogs sector to work together to try to create a UK standard which can act as the mark of a well-trained assistance dog."