Fears over detention centre staffing
But Eamonn O'Kane, general secretary of the NASUWT, the second biggest teaching union, said: "How will an NQT have been able to have gained this experience?"
He intends to raise the issue in talks with junior education minister Baroness Cathy Ashton.
The NASUWT, like the other major teaching unions, had argued that asylum seekers' children should be taught in local schools.
But the Government's controversial Nationality, Immigration and Asylum Bill was passed in November after the Lords dropped its opposition in return for other guarantees from David Blunkett, the Home Secretary. Mr O'Kane said his union had considered advising members not to take jobs in asylum centres, but rejected this idea.
"The important point for us is that only qualified teachers will be responsible for the education of these children," he added.
He said he had received that assurance in a reply to a list of questions put to the Home Office.
The Home Office replied: "The staffing mix in accommodation centres will mirror closely that of a typical maintained school.
"The majority of teachers will be required to have qualified teacher status, and, for teaching secondary school-aged children, an appropriate qualification in the subject taught wherever possible.
"Teachers will be supplemented by support staff such as interpreters, teachers qualified to teach English as a foreign or additional language, and bi-lingual classroom assistants.
"Accommodation centres will provide opportunities for teachers to develop their skills in teaching in a multi-ethnic environment which they can feed back should they return to mainstream schools."
Only four of the eight accommodation centres house children, of which two provide a modular education - Harmondsworth in Middlesex and Dungavel in Scotland.
The Home Office plans to open several more urban and rural centres in which asylum claims can be processed within six months.