School for autistic children in Tianjin
An child on the autistic spectrum looks out of the window at a specialist school in China's Tianjin municipality Reuters

A toddler has died at a Chinese rehabilitation centre for children who have autistic spectrum disorder (ASD) after taking part in a strenuous exercise regimen. The controversial facility in Guanzhou is said to make children walk 12 miles a day and "cure" patients through sweating in incubators.

The centre is run Xia Dejun, a self-educated medical practitioner who believes that ASD is a "rich man's disease". The first reports on the death of Lai Rijia, also known as Jia, said his cause of death was not "unnatural". But police are still conducting an investigation into the medical centre where the 3-year-old's body was found on 4 May.

Zhang's Wei, the boy's mother, is suing Xia and is concerned about other parents turning to alternative therapies to treat ASD.

"We had no other choice but to send Jia to this centre, as there was nothing else available," Zhang told the Telegraph. "For us, at least it provided a glimmer of hope."

Zhang said her son had died two months into a 21-month course at the centre, which opened in 2013. She also revealed that she saw a report saying her son had walked long distances.

The centre's website said that the children are required to walk 6-12 miles every day while wearing heavy clothing. The boy's mother also emailed pictures of her son wearing thick winter clothing, even though it was a hot day.

Xia's beliefs about autism are detailed in his book Notes on the Rehabilitation of Children with Autism. "There are more and more autistic children because we are better off than before and we treat children as 'little emperors,'" he says. "Parents become the slaves of children. Children from this kind of family become sick easily, and can easily become autistic."

Xia, who runs the centre had denied any wrongdoing. "Ask other parents. They will say my training works," he told Shanghai-based Sixth Tone. "The child died at a hospital from an illness. It has nothing to do with my rehab centre."

Four in every 1,000 children aged 6-12 in China fall on the autism spectrum, but the figure could be much higher. The statistics were announced at the 2015 International Meeting for Autism Research in Shanghai.

"Such data obtained at the national level for the first time shows that ASD is much more serious than we imagined. The figure is close to the incidence rate of epilepsy among children in China," Wang Yi, vice-president of the Children's Hospital at Fudan University in Shanghai told China Daily.