Four children were taken to hospital after teachers feared they had ingested cocaine believing it was a sweet powder similar to that found in a Sherbet Fountain. Dorset Police said that emergency services were called to Broadstone Middle School in Poole on 3 January 2017 after the children were found with the class-A drug.
The pupils, whose ages have not been revealed, told teachers they believed the cocaine was a sweet.
The emergency services were called and the children were assessed by South Western Ambulance paramedics before being taken to Poole General Hospital.
A probe is now under way to discover how the dangerous drug came to be found by the children.
Officers confirmed that a 32-year-old Bournemouth man had been arrested on suspicion of drug offences and was on police bail pending further enquiries.
A Dorset Police spokesman said: "The children believed the substance was sweets, but it has now been established it was cocaine. While it was not believed any of the children ingested the powder, they were taken to hospital to be checked over. They were assessed to be in good health and were discharged."
Headteacher, Dawn Wilks, told The Sun newspaper: "We can confirm that a child at Broadstone Middle School in Poole was found in possession of what was believed to be a drug. The children believed the substance to be sweets. The police were immediately called and four children taken to hospital to be checked over.
"They were not found to have any health issues and were discharged on the same day.
"We would like to reassure parents that this incident was dealt with swiftly and in line with our policies. Police enquires are ongoing regarding this incident and as such we are unable to comment further at this time."
Broadstone Middle School, for boys and girls aged nine to 13, was given the lowest Oftsed rating of "inadequate" following the most recent inspection in 2013.