A 10-year-old boy in Britain has broken a leg and kneecap of his schoolteacher by attacking her using karate-kick.

Diane Whitehead,53, could be off work for up to 18 months following the brutal assault by the boy at a school exclusion unit, the Daily Express reported.

The boy is also believed to have head-butted a second woman teacher at the school in south-east London.

Whitehead, a mother-of-two, is recovering in hospital after surgery to pin her shattered leg back together. It will be at least six weeks before she can walk again and doctors have warned her that she could be off work for up to 18 months.