Children in the poorest parts of the country are five times more likely to be excluded from primary school than those in rich areas, government figures show.
Pupils as young as five in poor areas are receiving thousands more suspensions than children in the most affluent neighbourhoods.
Also, the issue of poor children being excluded is more marked in primaries than in secondaries, the figures suggest.
The findings have led to renewed calls for compulsory tests of seven-year- olds to be dropped for fear that they contribute to poor behaviour.
Mick Brookes, general secretary of the National Association of Head Teachers, said that judging children as failures at an early age discouraged them from learning and led to increased behavioural problems.
"If they are told they are not achieving, it is not surprising that they rebel and end up being excluded," he said.
"We have to be more intelligent about how we describe children's progress. Public humiliation is something we need to avoid.
"If children are turned off education at an early age, our secondary colleagues will have no chance."
Mr Brookes also questioned whether there was sufficient expertise in primary schools to identify and help children with behavioural difficulties, including those on the autistic spectrum.
The figures show that primary schools in the 10 per cent most deprived areas in England gave temporary exclusions to 2 per cent of their pupils in the 2006-07 school year. That means there were 9,404 exclusions from 1,665 schools.
However, in the 10 per cent least deprived areas, schools exclude an average of just 0.4 per cent of their pupils, with 1,447 suspensions from 1,557 schools.
In secondary schools, there were more temporary exclusions overall, but the difference between the exclusion rates in poor and rich areas was smaller, not even double. The poorest secondaries suspended 13.7 per cent of their roll, compared to 7.9 per cent in the most affluent schools, according to figures released to the Liberal Democrats after a parliamentary question.
Seagrave Primary in Nottingham has employed a full-time outreach worker to focus on developing links with vulnerable families and tackling problems that can lead to poor behaviour, truancy and exclusions. Headteacher Michael Jackson says the outreach worker has helped to cut the school's exclusion rate.
"There is a gap between the kind of behaviour that will get a child excluded and the kind where social services will help. We are trying to fill that gap," said Mr Jackson. "But sometimes you have to exclude because children have to see that some behaviour is unacceptable."