At least 20 children have died and more are sick after eating free meals at a primary school in eastern India.

Bihar state official Abhijit Sinha said another 27 children and the school cook were in hospital in Patna, the state capital, 10 of them in a serious condition.

The children, aged between eight and 11, fell ill yesterday soon after eating meals in the school in Masrakh, a village 50 miles north of Patna. They were rushed to a local hospital and later to the state capital for treatment.

The meal was cooked in the school kitchen, but school authorities stopped serving the meal as children started vomiting.

PK Sahi, the state education minister, said a preliminary investigation suggested the food of an organophosphate used as an insecticide on rice and wheat crops. It's believed the food was not washed before it was served at the school.

Malnutrition is one of the major health concerns among Indian youngsters and many state governments have launched midday meal programmes for poor children.

Bihar state chief minister Nitish Kumar has ordered an inquiry and authorities have suspended a food inspector and registered a case of criminal negligence against the school's headmaster.