City academies in one of the most deprived areas of Britain are expelling significantly higher numbers of students than other schools, File On 4 reports.
The Prime Minister has called academies 'social action in justice'
The King's and Unity City academies in Middlesbrough have expelled 61 problem pupils between them since the start of the school year in 2002 , compared to just 15 from all other secondary schools in the borough.
The expulsions appear to undermine the government's declaration that academies are committed to educating the most disadvantaged and difficult children.
They also mean neighbouring schools have to pick up the cost of taking on the students, while the academies keep the money for their education for the rest of the year.
King's has expelled a total of 27 children since opening in September 2003, with up to ten others withdrawn by their parents under the threat of expulsion.
In the same period, Middlesbrough's seven non-academy secondary schools expelled only 10.
The mother of a son who arrived at King's with established behavioural problems, told File On 4 that after his first half-term she was given two options: either remove him from the school herself or he would be permanently excluded.
She claims he was not given long enough to adjust.
"He went up there with a bad record and they said: 'This lad isn't going to work. Let's get rid of him.'"
The principal at King's, Nigel McQuoid, said the high number of pupils leaving his school was down to "a blip in establishing a level of education that wasn't here before."
But local head teacher Richard Bain questioned King's expulsion policy.
"It looks as if they are using permanent expulsion as a means of frightening parents and children into behaving in the way in which they wish within the school," he said.
Middlesbrough's other academy, Unity City, expelled 18 students in 2002 - 2003, its first year, and 16 the following year.
All the pupils expelled or removed from both academies became the responsibility of the local education authority which sent many to neighbouring schools.
An academy which expels a student is able to keep the money for their education for the rest of the year. Not only is the same privilege denied a non-academy school, but it receives no payments for the extra pupils it absorbs.
The Unity City Academy provides state-of-the-art facilities
Mr Bain said: "I do think that had the [King's] academy had the discipline of knowing that it was loosing £3,000 every time it excluded a child, it would not have excluded 27 children."
A senior councillor at the local authority, Michael Carr, pointed out that expulsion itself is contrary to the government's policy that permanent exclusions should be avoided wherever possible.
"Only in extreme circumstances should children be excluded, or it becomes a process of selection post facto," he said.
File On 4 also gathered statistical evidence that of the UK's original three academies, of which Unity City is one, two are failing to recruit the most disadvantaged group of local children.
Professor Stephen Gorard of York University found that the number of students entitled to free school meals at Unity was 47%, compared with figures near 60% at it's predecessor school.
"More significantly," he said, "now four other schools in the area are taking a higher proportion of children with free school meals."
The Greig City Academy in Haringey, north London, did not have the highest levels of disadvantage in the borough before it opened in September 2002, and still does not.
But the Bexley Academy in South London still recruits the same proportion of disadvantaged children as the previous local school.
Schools Minister David Miliband said the academies were successfully targeting the neediest children.
"The academies' programme is not about changing children, but about changing the provision for them."
File on 4: BBC Radio 4, Tuesday 23 November at 2000 GMT and repeated at 1700 GMT on Sunday 28 November.