The guidance, produced in consultation with the Home Office Immigration and Nationality Directorate (IND) and roundly decried as a "snooper's charter" when first mooted last year, recommends that admissions authorities and headteachers voluntarily pass on information of "suspected immigration offenders".
Its legal justification is the Data Protection Act, which permits disclosure of information in order to prevent or detect an offence.
The guidance states "if reasonable suspicion is aroused that an applicant may be in the UK without permission, consideration should be given to telling the Home Office Immigration and Nationality Directorate about those suspicions. "
Among the factors that could arouse suspicion, says the guidance, are applications made "outside the usual admissions cycle", absence of previous school records and "the lack of contact with the child and parent themselves".
Peter Smith, general secretary of the Association of Teachers and Lecturers, said: "The notion that headteachers and teachers should be licensed narks is horrific. It's the duty of teachers to teach - not to carry out immigration checks."
The Secondary Heads Association's John Sutton, who is preparing a response to the consultation document, predicts that his members "will want nothing whatsoever to do with this guidance. It is widely regarded with acute distaste and will fail because of passive non-co-operation."
David Hart, of the National Association of Head Teachers, said: "The Government will get a considerable thumbs-down from heads and governors on this."
Equally implacable is the National Union of Teachers, which insists that "it does not want to be treated as an arm of the immigration authorities".
Welfare organisations fear that the guidance, if heeded, would extend a practice already being operated by some local authorities. Jill Rutter, education officer at the Refugee Council, said: "I would guess that there are somewhere in the region of 200 cases a year of asylum-seeker families already being turned away by schools and admissions authorities, who are taking matters into their own hands."
"This would be giving authority to a lot of untrained people to be checking documents that they didn't understand and in the process, would be eroding the trust between parents and schools that is essential for good home-school liaison."
The consultation period for the draft guidance ends in mid-August.