An Indian court Monday sentenced a school principal to 17 years in jail over the death of 23 pupils who were served a free meal laced with pesticide, a prosecutor said.

The head of the government-run school was found guilty last week of culpable homicide for the 2013 tragedy. In all, nearly 50 children consumed the poisonous lunch in Saran district in the eastern state of Bihar.

‘Meena Devi was sentenced to ten years for culpable homicide and seven years for attempt to commit culpable homicide,’ public prosecutor Sameer Mishra told AFP.

Devi was also fined 375,000 rupees ($5,500), with much of the money intended for the families of 24 injured children.

Prosecutors said they were satisfied with Monday's ruling but would challenge the court's acquittal of her husband Arjun Rai for lack of evidence.

Rai allegedly supplied the pesticide-laced oil used to cook the meal.

Investigators told the court Rai had stored the pesticide alongside the cooking oil, and supplied the contaminated oil to the school.

He had secured the contract for school supplies from his wife without following any guidelines, investigators said.

The children, aged four to 12, fell ill within minutes of eating the lunch of lentils, potatoes and rice at their primary school in the poverty-stricken village of Dharmasati Gandaman on July 16, 2013.

‘We were hoping both of them would be jailed but the court let her husband off,’ Madav Ram, father of a 12-year child, who died, told AFP.

The disaster prompted the government to improve food safety in schools. Children often suffer food poisoning due to poor hygiene in kitchens and occasionally sub-standard food.

Free lunches have since 2001 been offered to some 120 million schoolchildren throughout India, in the world's largest school meal programme.

Educators see the scheme as a way to stop children dropping out of school, in a country where almost half of all young children are undernourished.