Hidden children 'serious problem'
Schools can often pick up on children's problems
MPs and voluntary organisations have said there is a serious problem of children in need slipping "under the radar" of social services.
Many do not get help because they are not known to the authorities or keep their problems from them, MPs heard.
The Commons children's select committee heard that homeless youngsters, those in care, young carers or trafficked children were most at risk.
Schools and GPs could do more to help, children's charities told the MPs.
Labour MP Fiona Mactaggart, who chaired the committee, said: "We have a pretty clear picture that this is a not a small scale problem, that it's a serious problem.
"The view of all our witnesses is that there is a key issue of professionals being able to connect with young people and listen to them and give them a voice."
'Particularly cruel'
Kathy Evans, policy director at The Children's Society, told the MPs there were concerns about two groups of children - those in touch with social services who were going to school or the GP but whose needs were not being spotted, and those who were disengaged from services.
"We have a lot of questions about how do we helpfully and ethically but proactively seek to find out whether there are any problems at home for children," she said.
Groups of children who might have hidden needs could include gypsy or traveller families, young carers or refugees and disabled children placed away from home, she said.
John Reacroft from the charity Barnardo's said children living in temporary accommodation often moved frequently and slipped "under the radar" of services.
If you are homeless your needs are increasing as a family but your access to services can often decrease
John Reacroft Barnardo's Children might end up out of school and without access to GPs, community support or day centres, he said.
"It's particularly cruel because if you are homeless and in temporary accommodation, your needs are increasing as a family but your access to services can often decrease because many families are housed very long distances from where they originated."
Mr Reacroft said there was a particular problem when local authorities moved a homeless family out of their area into private accommodation in another.
Local authorities now had a responsibility to pass on details of people being moved into another area - but that did not mean they would then get the support they needed, he said.
Another key factor in children slipping through the net was fear, the committee heard.
Children were afraid that telling anyone about their family problems might lead to its being broken up and their being taken into care, said Kathy Evans.
Box of chocolates
Schools and GPs were often in a good position to pick up on family problems but did not always do so, said Dr Jo Aldridge, director of Young Carers Research Group at Loughborough University.
"School is critical here. There used to be people who were more obvious in schools - educational welfare officers. They now seem to have much bigger case loads and who is there to deal with the welfare of the children?"
"A lot of teachers don't see that as their role or feel uncomfortable."
Dr Aldridge said some teachers needed more training on how they should respond if they found out a child was caring for a parent at home or had a parent who was mentally ill.