Parents are initiating legal action against the government over multimillion-pound cuts to special needs funding in England, amid warnings of “a national crisis” affecting thousands of children with disabilities across the country.

Two families from East Sussex and North Yorkshire with children with special educational needs are the latest to launch a crowdfunding appeal to bring a legal challenge to cuts.

Earlier this year, families in Surrey, Bristol and the London borough of Hackney began legal action against their local authorities after they announced substantial cuts to special educational needs and disabilities (SEND) budgets.

This time, parents are seeking to take ministers to court because they say government policies are leaving local authorities with insufficient money to fulfil their legal obligations to SEND pupils.

Specialist lawyers have been called in to investigate potential legal grounds on which to challenge the government. Parents, meanwhile, are urging the education secretary, Damian Hinds, and the chancellor, Philip Hammond, to increase funding to local authorities to ease pressure on SEND budgets.

One of the parents involved in the action, Lorraine Heugh, of Robertsbridge, East Sussex, said: “Families can’t sit back any longer and watch this unfold. It is obvious that councils do not have enough money because of the funding they receive. Cuts to SEND budgets are being made across the country. It has got to the point now where this is a national crisis.”

Her son Nico, 15, has autism and anxiety and requires specialist educational care to remain in a mainstream school, but Heugh said funding had been reduced. She said other children were forced to spend years out of school as their parents fought for an appropriate placement.

“Nico is at a key stage of his education and his upcoming GCSEs will go a long way to determining his life chances. He should be able to concentrate on these but instead we are once again battling for him to receive the support he needs.”

Cash-strapped local authorities are increasingly finding themselves under pressure from all sides over SEND funding. Earlier this month, Bristol city council was forced to cancel planned cuts of £5m to its SEND budget after a court ruled the council had acted illegally.

Next week, a judicial review to decide the legality of Surrey county council’s planned cuts of more than £20m from SEND services is due to be heard in the high court. A similar hearing into Hackney council’s plans is scheduled for next month.

Anne-Marie Irwin, from the law firm Irwin Mitchell, which is representing the families, said: “Through our work in helping families of children with special educational needs we have seen the increasing strain local authorities are being placed under because of budget cuts.

“The families are concerned that local authorities are not receiving enough funding so wish to investigate whether there are legal grounds to challenge the government over its funding support.

“They believe that thousands of children across the UK with special educational needs are currently unable to receive the support that they need.”

The family of Benedict McFinnigan, 14, from Scarborough in North Yorkshire, are also seeking to take the government to court. Benedict has post-traumatic stress disorder, anxiety, depression and chronic insomnia. He has not attended a mainstream school for two years and spends less than three hours a day at a pupil referral unit.

His mother, Kirsty, said: “It is clear that the number of children with disabilities not being able to receive the help they need is growing. If councils and headteachers across the country are telling us they don’t have enough money there is clearly a national problem.

“The money comes from the top with regards to the government so we want to take our fight for change to the top.”

Latest official figures show the number of pupils with SEND has increased for a second consecutive year and they represent 14.6% of pupils, up from 14.4% last year. Pupils with SEND are up to six times more likely to be excluded from school and account for almost half of all permanent exclusions.

The children and families minister, Nadhim Zahawi, said: “Our ambition for children with SEND is exactly the same for every other child, to achieve well in school and college, find employment and go on to live happy and fulfilled lives.

“We have introduced education, health and care plans, putting families at the heart of the process and providing support tailored to individual needs. But due to increasing costs, we recognise there are pressures on high-needs budgets.”