Hundreds of disabled children were injured in schools while being physically restrained, an investigation has found.

Pupils were pinned face down on the floor, strapped into chairs, suffered broken bones and one had their head covered with a "spit hood", according to 5 live Investigates.

There were around 13,000 restraints resulting in 731 injuries in Britain over the last three years, according to a Freedom of Information request by the programme.

Only 37 of the 207 local authorities in England, Scotland and Wales were able to provide the data, which means the actual figures could be much higher.

Beth Morrison, from Dundee in Scotland, is campaigning for new guidance and training after her son Calum was injured while being restrained.

She said he came home from his special school with bruises on his arms and marks on his chest, which was allegedly caused by him being held face down in a prone restraint.

"The GP said it was called a petechial haemorrhage rash and these rashes, and where they were on his body, indicated that there was some indication of positional asphyxia," she told the BBC.

"These injuries are often seen in victims of hanging and in strangulation - so that was very, very serious."

Dundee Council said there is an ongoing police investigation into Callum's case.

The Department of Education said it plans to issue new guidance on restraining children with learning disabilities, autistic spectrum disorders and mental health difficulties.

"The protection of children is of the utmost importance and any instances of restraint being used inappropriately must be reported," a spokesman told the BBC.

Dr Brodie Paterson, a specialist in handling vulnerable people, said many children are lucky not to be killed by the methods used.

"The worrying thing is that we have no idea how many near-misses we have had, but I have certainly come across scenarios where I think the child was lucky to survive the restraint," he told 5 live.

"It's really important that schools are transparent about the use of restraint, it's really important this data's available nationally."

The story will feature on Radio 5 live Investigates on Sunday at 11am.