A forensic report has found that oil used to cook a school lunch that killed 23 children in India contained a powerful insecticide.

The pupils died after eating a free school dinner of lentils, potatoes and rice, which contained an agricultural insecticide that was five times stronger than that sold commercially.

Some 24 children and a cook are still being treated in hospital, but doctors believe they're out of danger.

Officials are still investigating how the poisonous substance ended up in the oil.