Police said an investigation was under way after eight children at the camp at Stathern Lodge were taken to hospital on Sunday. All have since been discharged.
Officers had gone to the camp, in Canal Lane, with East Midlands Ambulance Service after receiving reports about the children feeling unwell.
The arrested man was detained on suspicion of administering poison or a noxious thing with intent to injure, aggrieve or annoy. He remains in custody.
The police watchdog, the Independent Office for Police Conduct (IOPC), said it was investigating Leicestershire Police’s handling of the incident.
‘Delayed police response’
Police said once emergency services had arrived at the scene, a triage centre was set up at Plungar Village Hall to assess all children present at the camp.
Following an initial assessment, eight children were taken to hospital as a precaution and all have since returned home.
The force said the investigation was now being led by the East Midlands Special Operations Unit’s major incident team.
Officers remain in Stathern on Thursday, carrying out further inquiries and providing reassurance to families affected.
Meanwhile, an IOPC spokesperson said it received a “conduct referral” on Tuesday from the force “relating to their handling of concerns passed to them over the wellbeing of a group of children”.
“Our assessment team has examined all available evidence and concluded the matter should be independently investigated by the IOPC,” they said.
“The investigation will look at whether there were any breaches of professional behaviour – namely a failure to carry out duties and responsibilities – that resulted in a delay in Leicestershire Police’s response to what was later declared a critical incident.”
