Keith Towler took over the commissioner's role in March
The fundamental human rights of children held at an asylum detention centre have been breached, Wales' Children's Commissioner has said.
Keith Towler said he had been shocked some youngsters had been held for months at Yarl's Wood in Bedfordshire.
In his first annual review, he said some of the children had returned to Wales 'traumatised'.
He also said policies aimed at helping children and young people were failing to make a real difference.
The commissioner said children he had spoken to had complained about the searches at Yarl's Wood, as well as its healthcare and food, and not being allowed to go to the toilet on long journeys.
He said he had raised the matter with ministers and intended to visit and inspect the conditions in which children who were ordinarily resident in Wales were held.
Mr Towler took over the commissioner's role in March. The post made Wales the first part of the UK to appoint an independent children's commissioner when it was created in 2001.
It would be a real pity if we do not have the courage to recognise the problems and take whatever action necessary to close those gaps
Keith Towler, children's commissioner for Wales
He quoted one child who described being taken to Yarl's Wood in a car journey lasting more than four hours, saying: "I was sick in the car. They didn't stop."
Mr Towler said his office had acted on behalf of a number of sick children who were refused medical care because they were seeking asylum and had "no status".
He said: "I have been shocked by the lack of respect and the fundamental breaches of children's rights in the asylum and immigration system."
He said he was "disappointed" that regulations had not been changed to give young asylum seekers equal access to education and he was taking legal advice on the matter.
The commissioner said some youngsters being charged overseas student fees at university and were not receiving education maintenance allowances even though some had lived in Wales for a large part of their childhood.
In his annual review, Mr Towler said the gap between policies and services in Wales was evident despite the good intentions of those trying to implement them.
He blamed some of the problems in delivering services on inadequate funding, with many projects not knowing whether they will still be there from one year to the next.
In a bid to solve the problems he identified, the commissioner said he would provide encouragement and support for services, but would not accept excuses.
"The fact that this gap is evident across a number of policy and service areas, in different parts of Wales, is a regular feature not only of news coverage but of advice and support cases brought to my attention, underlines the need to recognise the problem and look for ways to address it," he said.
"Having made the progress we have in Wales, it would be a real pity if we do not have the courage to recognise the problems and take whatever action necessary to close those gaps.
Mr Towler is travelling across Wales to raise awareness about his role. He will be asking children and young people for their views.
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