Child migrants claiming a legal right to live in the UK are at risk of suicide through delays in resettlement after the demolition of the Calais Jungle camp, a charity has warned.
Citizens UK said the pause in transfers from France over the last week meant many were suffering a "significant deterioration" in their mental health.
It said 15% of those in Calais at the time of the camp's demolition had arrived, with some 1,600 young migrants and refugees transferred by bus to 60 centres across France.
Some 300 unaccompanied children have been brought to Britain and the Government is committed to transferring hundreds more, the Home Office said.
Citizens UK said of 40 children they are supporting in France, one third have expressed suicidal thoughts and lack of care of their own life since the demolition, 75% have showed an alarming deterioration in mental health and 90% have reported increased anxiety.
Dr Susannah Fairweather, a consultant psychiatrist who has worked as an independent medical witness assessing unaccompanied minors in Calais, said further delays were creating a "cumulative trauma" which would make settlement more difficult once they do arrive in the UK.
And she said the country was not prepared enough to deal with the "complex" issues that many experience.
She said: "The delay can cause significant deterioration in the children's mental health, including the stark risk of suicide.
"In addition to this, it is my observation that the young people who have lived in the unstructured, informal camp for a prolonged period of time find it particularly difficult to adjust to life in more ordinary circumstances.
"It's cumulative trauma which has a much more disturbing effect on young people's development. It's toxic for them.
"I don't think the UK is prepared for all their different needs. It needs to be a multi-agency approach with social services, mental and physical health services and legal services. Everybody needs to work together.
"Certainly I don't think there's direction."
Citizens UK will stage a demonstration outside the Home Office's Lunar House in Croydon on Sunday afternoon to urge that the transfers resume immediately.
Volunteers and faith leaders will hold up pictures of children waiting to be transferred.
A Home Office spokeswoman said: "We are working closely with the French government and other partners to identify unaccompanied asylum-seeking children who are eligible to come to Britain.
"Our focus is, and will continue to be, transferring all eligible minors to the UK as soon as possible and ensuring they arrive safely."
Children's eligibility under the Dublin regulation or Dubs amendment would be considered at the temporary centres in France and transfers would resume in the "coming days and weeks", she added.