Local authorities pay pounds 14m each year for administration and alternative lessons and support, while social services pay pounds 3m for support. In addition, one-quarter of out-of-school pupils get into trouble with the police, costing around pounds 7m a year.
Last week Gillian Shephard, the Secretary of State for Education and Employment, announced that 11,000 pupils were permanently excluded from schools in the 1994-95 academic year. Dr Carl Parsons, who carried out the research released yesterday by the Commission for Racial Equality, believes the figure is now even higher.
Although the cost of looking after excluded pupils is far higher than for those who stay in school, they receive an average of only half a day's teaching per week.
Only 15 per cent ever find their way back into mainstream schools. Some go to pupil referral units, some receive home tuition and others simply drop out of the education system altogether.
One pupil in one of the six local authorities visited by a team from Christchurch College in Canterbury, Kent, cost social services pounds 39,000 in a single year, including a place at a residential school, and cost the criminal justice system a further pounds 22,000.
The commission is concerned about the issue because black boys are six times more likely to be excluded from school than their white classmates. Yesterday its chairman, Herman Ouseley, called for changes in the law which would curb a recent rapid rise in exclusions.
Proposals in the Government's latest Education Bill which would allow schools temporarily to exclude pupils for up to 45 days in a year should be dropped, he said, and appeals panels should be forced to consider the cost of exclusion.
The report, Exclusion from School: The Public Cost, also gives details of the social costs of removing a child from school. Researchers who interviewed 27 parents of excluded pupils reported that they suffered from stress, worry about how to cope with their child during the day and fears about the disruption to their education. In the long term, family strains could lead to divorce or to the child being taken into care.
Mr Ouseley accused schools of using exclusion in a "trigger-happy" way. "People are using exclusion as a first option rather than as a last option. You have to bear in mind the home cost, the damage to family, the stress to other agencies such as criminal justice and social services," he said.
His remarks drew an angry reaction from the teachers' union which has been to the forefront of several high-profile campaigns for more exclusions of disruptive pupils.
Nigel de Gruchy, general secretary of the National Association of Schoolmasters/ Union of Women Teachers, said the costs of disruption to other children's education if these pupils were kept in school were incalculable. Research to be published soon by his union would show that between 80 and 85 per cent of excluded pupils were already in trouble with the police, he added.
"This is rubbish. I think schools tolerate far too much. If we were exclusion- happy there would be hundreds of thousands of kids chucked out every year," he said.