Image caption Paul McDonald estimates his son has been suspended for 135 days of his first four years at school

Paul McDonald's autistic son, Jim, has been suspended from his mainstream primary school for 30 days in the past three months.

But that is just the tip of the iceberg.

Paul estimates that Jim, aged eight, has been suspended for 135 days of his first four years at school.

He is among a group of parents set to meet the Department of Education (DE) to highlight the similar problems their autistic children are facing.

The proportion of children with autism in Northern Irish schools has almost trebled in a decade, according to the Department of Health.

And some parents, like Paul, say that means they have to battle to get appropriate support in school for their children.

Image copyright Getty Images Image caption The proportion of children with autism in Northern Ireland schools has almost trebled in a decade, according to the Department of Health

"Jim's very curious about the world, he loves knowing how things work and likes to hear other people's thoughts on things," he said.

"His autism is autistic spectrum disorder (ASD) with pathological demand avoidance (PDA)."

"The majority of the problem that Jim would present with would be anxiety, so as soon as you give him a direct demand he would experience anxiety and as a result of the anxiety he would start refusing."

Autism is a spectrum, which means people with autism can present with different conditions.

Some may need little or no support, but others may need sustained help.

According to documents seen by BBC News NI, Jim has been suspended for school for 30 days since 28 March, often for five days at a time.

Image copyright Getty Images Image caption People with autism present with different conditions, some may need no support while others need sustained help

Paul admits Jim presents challenges and would sometimes lash out at his teachers, but said it was due to his rising anxiety.

"He would become quite distressed within the classroom environment and, as a result, he would throw something, say certain things and then it moved on to lashing out," he said.

Jim has a statement which says that he needs a full-time classroom assistant and would learn best in a small group setting like a learning support unit.

However, he has also faced expulsion, but Paul said that if staff had the appropriate training about Jim's condition then he could thrive in his current school.

"The strategies you would use for PDA are different than those you would need for a 'normal' ASD child," Paul said.

"For instance, you avoid using the word 'you' towards Jim."

"If Jim did something well you would turn round and say 'I like what has been done there', instead of 'I like what you did there'."

"We could very clearly see there were patterns to how the situation escalated resulting in Jim getting suspended."

Paul is now one of a group of more than 100 parents who are in contact as their autistic children have had similar experiences in school.

Tanya George's son 11-year-old son, Niall, has also missed substantial amounts of education in primary school.

Image caption Tanya George's son has missed substantial amounts of education in primary school

He finally received a diagnosis of ASD in July 2018, just as he finished Primary Six.

He was then able to go to his mainstream primary for three days a week, with the help of a classroom assistant.

But Tanya said she was aware that Niall needed support much earlier in his school career, and had often put himself in danger at school.

"In the past he's got extremely overwhelmed and he's got so stressed that he's had to run out of the room, into fields and in front of cars," she said.

"His flight response is really, really triggered at that point when his anxiety is so great.

"A child doesn't present like that for no reason."

"Any child that would have those issues you should be looking at helping and supporting and resolving the child to get through it."

She also said that at times she felt pressured to withdraw Niall from school altogether.

Tanya said, though, that since receiving a dedicated classroom assistant following his diagnosis and completed statement Niall has progressed and is now looking forward to post-primary school.

The Education Authority now spends £270m a year on supporting children with special educational needs - including autism.

Image caption Liam Mackle of the Children's Law Centre says an increasing number of parents are challenging the level of support their children are receiving

That is around one-eighth of the entire yearly education budget.

DE's permanent secretary Derek Baker has previously said that he is worried about the rising cost and the support offered to children with special educational needs.

And according to Liam Mackle from the Children's Law Centre in Belfast an increasing number of parents are challenging the level of support their children are receiving.

"There are pockets where schools don't yet understand the complexity of autism - each child with autism is completely different from the next child with autism," he said.

"It's about identifying what triggers are, speaking to the experts at the EA in terms of their autism intervention services and putting proper school-based strategies in place to avoid the need for things like suspensions and detentions which aren't addressing the problem."

"Special educational needs and provision for children particularly with autism has really in the last five years, in terms of our advice service, really exploded.

"Five years ago we were dealing with just under 400 cases in terms of special educational needs - including autism - and that's now jumped to 1600."

Mr Mackle's experience is borne out by figures from the Department of Justice, which shows that the number of appeals to the Special Educational Needs and Disability Tribunal (SENDIST) has more than doubled in recent years.

In 2015/16 there were 145 appeals to the tribunal - which rules in cases where parents are unhappy with how the EA is dealing with their child's special educational needs.

By 2018/19 that had risen to 378 appeals, and just over half of those cases to reach a hearing were won by the parents.