Teachers in Bihar state in India boycotted a free school lunch scheme on Friday to protest against the arrest of the head of a school where 23 children died after eating a meal last week.
A union spokesman said 90% of the 300,000 employed at state-run primary schools took part in the boycott. But education officials said only 20% of schools went without the meal.
About 16 million pupils are given free lunch at 70,200 primary schools in Bihar.
The BBC reports the Mid-Day meal scheme reaches 120 million children in 1.2 million schools across the country. It provides free food for pupils, but often hygiene is poor.
Last week, 47 children, aged between five and 12, were taken ill after eating a free meal of rice and soya beans in Saran district. Twenty three died in hospital.
The BBC reports high levels of an agricultural insecticide were found in samples of the food they ate.
School principal Meena Kumari was arrested on Wednesday. Police intend to charge her with murder and gross negligence.
"We'll stay away from this Mid-Day meal scheme which is getting us a bad name," primary school teachers association president Brajnandan Sharma told the BBC.
''We are always made the scapegoat whenever an incident happens, but there is huge corruption in the way it is run.
''We feel sorry for the students, but there is no option left for us," he added.