Academies expelled pupils at twice the rate of other secondary schools last year, official figures have revealed.
It remains the case that behaviour is generally good
The numbers have not been included previously in the annual exclusion statistics, and were not in the set issued last month for the year 2005-06.
Now added, they show academies permanently excluded 5.5 pupils in every thousand, compared with a rate of 2.4 in other secondaries in England.
The government says this is because academies have "challenging intakes".
The figures published by the Department for Children, Schools and Families are those given by academies and city technology colleges themselves and are unconfirmed, it says.
The totals involved are small, as only relatively few academies are open: there were 140 permanent exclusions in total.
In 2002-03 there were 30, but this was almost 10 per thousand pupils, and the rate has been dropping dramatically since.
There were also 3,990 fixed period exclusions - which may involve the same youngster more than once.
Those temporary suspensions were 16% of the school population, compared with 10% in other secondary schools.
The update to the exclusion statistics also gives a breakdown by ethnicity.
This indicates that, among groups of any size, children of black Caribbean heritage were the most excluded (four per thousand), closely followed by those of mixed black Caribbean and white heritage (3.6 per thousand).
The figure for the white majority was 1.3 per thousand and, at the other end of the scale, just 0.4 among Indian pupils.
Children's minister Kevin Brennan said: "Academies tend to have higher exclusion rates than average when they first open.
"This is because they often have very challenging intakes and are taking over from weak schools in disadvantaged areas where standards of behaviour were unacceptable.
"We support heads in using fixed period and even permanent exclusions as a tool to regain discipline and thanks to our reforms these are very rarely overturned on appeal."