Schools could be forced to keep violent and disruptive pupils in class for up to 16 weeks as the Government attempts to cut the huge number of children being excluded.
Teachers' leaders have warned that the Government's idea of "pastoral support plans" for pupils facing exclusion is a recipe for conflict.
Permanent exclusions have risen six-fold in the past seven years to more than 13,000 a year.
Pastoral support plans (PSPs) are intended to help pupils improve their behaviour. The pupil reaches an agreement with staff and is set clear discipline targets.
The proposals, contained in draft regulations, "Social Inclusion: Pupil Support", are expected to come into force this June. The consultation period ended today.
They indicate that unless schools have tried to improve an excluded pupil's behaviour by using a PSP, governors should allow them to return to school.
The National Union of Teachers favours support plans, but fears that the regulations are too prescriptive and could increase tensions between parents, pupils and schools.
The union says that governors could come under pressure from parents to reinstate excluded pupils who have been dealt with fairly under a school's disciplinary procedures though not given a support plan.
In its response to the guidance, the NUT said: "It may be intolerable for other pupils, staff and parents to have to wait for 16 weeks to see if a PSP works for a pupil who ought to be subject to permanent exclusion immediately."
Doug McAvoy, general secretary of the NUT, said: "Where children are genuinely dangerous to pupils and teachers they must go. There must be no bureaucratic hurdles."
The union is also concerned that there is no new money behind the scheme and about the likelihood of extra paperwork.
It has asked the Government to provide enough cash to give schools the option of using PSPs but to avoid compulsion.