More resources must be made available to help migrant children integrate better into Northern Ireland schools, a social partnership group has said.
Migrant pupils can find it difficult to mix in the classroom
Concordia said the government has failed to tackle the issue.
It said the number of migrant children in Northern Ireland schools had risen sharply within the past two years.
The group said many migrant children were being let down over "inadequate provisions" to help them learn English and become involved in school life.
Concordia, which represents business, trade unions, agriculture, and the voluntary and community sectors, said many schools had experienced a cutback in English as an Additional Language (EAL) tuition services over the past year.
Tom Gillen, a Concordia board member and senior trade union representative, said: "For months, the government has been promising the teaching unions that it will fund a new centralised EAL service, but we've heard nothing more.
"We know many schools have been struggling to provide proper support and English tuition to the increasing number of migrant pupils arriving at Northern Ireland's schools, and that some of those children are losing out as a result.
"This increase in numbers has come at a time of unprecedented financial pressure on the education boards.
"The response of both the boards and the government to date has been ill thought-through and inadequate."
Concordia is calling on the government to provide sufficient funding to enable the education boards to employ adequate numbers of specialist staff.
It also wants the government to develop a clear and coherent policy on the provision of such support.
One school which has faced problems is Monkstown Community School in Newtownabbey, County Antrim.
Principal Denis Harvey said the school has struggled to cope with the needs of the 15 migrant pupils currently on its roll, most of whom arrived at the start of the school year.
"We have no experience and no training in providing support to children whose first language isn't English," he said.
"We've been relying purely on the individual interest of certain teachers."
At the start of the school year, most of the migrant children at the school had little or no English.
The school decided to use some of its own resources to fund a two-week intensive programme of English tuition which it organised for the children.
Mr Harvey added: "The lack of adequate provision has had an impact on them. Some of them have become very sociable and have proved to be very good at integrating into the system.
"But others are really quite isolated. They find it difficult to mix, and the local children find it difficult to mix with them because of the language barrier."
The school receives a visit from an EAL specialist provided by the North Eastern Education and Library Board once a fortnight, but staff said this was not enough to enable all the children to become sufficiently fluent in English.