More than 60 students were hospitalized in the city of Tripoli after drinking contaminated tap water.
The students, all below 12 years of age, were taken to a hospital after suffering from pain in the abdomen, vomiting, diarrhoea and breathing difficulty.
The children are students of Hayy al-Nozha school, Xinhua reported citing Voice of Lebanon radio.
The results of medical tests will be revealed Friday, he said.
In a similar incident in May last year, several students and a teacher in a public school suffered from food poisoning after having lunch during a school trip.