A significant number of councils and health services are failing to identify mental health issues when children enter care, a select committee report has found.
The House of Commons' education committee found child and adolescent mental health services were ‘turning away' young people in care because the children were without a stable placement.
It warned this was against statutory guidance which says looked-after children should never be refused a service on the grounds of their placement.
Neil Carmichael, chair of the committee, said: ‘Local authorities have a special responsibility for the welfare of looked-after children.
‘In spite of this duty, it's clear that many looked-after children in England are not getting the mental health support they need.'
Responding to the report, the Local Government Association's community wellbeing spokeswoman, Cllr Izzi Seccombe, said: ‘We recognise that improvements urgently need to be made to the mental health services available to all children, in particular those in care.
‘However, to provide the level of support required, we need a joint approach with every organisation involved in a young person's life, such as schools, carers and health services, as well as councils.'
Cllr Seccombe noted Whitehall's Future in Mind programme provided a joint approach but warned it was under-funded.
She continued: ‘This vision needs to be backed with proper funding, which at the moment is around just 6% of the NHS mental health budget and 0.7% of its overall budget.
‘Clearly more investment is needed if we are to deliver the mental health support our children and young people need and deserve.'
