Around half of pupils who have been expelled from school have a mental health issue, new figures show.

The Institute of Public Policy Research suggested that those figures could be much higher, as many mental health issues go undiagnosed.

Official figures show that around one in every 50 children has a mental health condition.

However, the number of pupils being expelled has risen each year, suggesting that poor mental health in schools is escalating.

According to the research, 35 pupils were excluded every day in 2015/16 – five more daily compared to the year before.

IPPR associate fellow Kiran Gill, founder of The Difference campaign on the issue, said: “Theresa May says she is committed to improving mental health of young people.

“Addressing the most vulnerable children being thrown out of England’s schools is a good place to start.

“Because unequal treatment of mental health may be an injustice, but the discrimination of school exclusions is a crime.

“If the government is serious about real action on mental health, there needs to be dedicated funding and thought-through solutions rather than sticking plasters in the symptoms of the problem.”

A Department for Education spokeswoman said: “Any decision to exclude must be lawful, reasonable and fair and we are clear permanent exclusion should only be used as a last resort, in response to a serious breach or persistent breaches of the school’s behaviour policy.

“”This government is committed to working with local authorities and schools to ensure children in alternative provision receive a high-quality education.

“We are strengthening the links between schools and NHS mental health staff and have announced plans for every secondary school to be offered mental health first aid training.”