THE length of time young offenders have been locked up on their own has “dramatically” increased, the human rights select committee heard today.

Despite the overall number of children being detained falling, a study by the Office of the Children’s Commissioner for England found that the average length of periods of segregation has doubled from eight to 16 days since 2014.

With 70 per cent of episodes of segregation lasting over a week, Children’s Commissioner Anne Longfield highlighted concerns whether youth custody was always the most appropriate setting.

All youth offenders institutions (YOIs) in England reported at least one instance of segregation of 75 days or more.

Accounts of children spending up to 23.5 hours in a cell daily were recorded, which the report says would appear to contravene Articles 37 and 40 of the United Nation’s Convention in the Rights of the Child.

A child from a YOI reported feeling “upset and anger” at being put into isolation.

“I’ve gone from being out of my pad all day to being isolated, well locked up really, for three days straight, so there was a lot of emotions going through my head,” they said.

“I didn’t really know what was going on. I was up and down, I was angry smashing up my pad and stuff like that.

“I ended up tying something round my neck and dropped to the ground.”

Gang involvement, prison staffing levels and shortages of NHS mental health beds may be driving the increase, the report said.

Ms Longfield has called for more “transparency and accountability” around the use of segregation in the youth justice system.