Tablets were brought into one of Merseyside's most prestigious schools and were taken by a child, sparking a police investigation.
Officers were called to Merchant Taylors' school in Crosby earlier this week following concerns about substances on the premises.
A child is believed to have consumed one of the tablets, but is understood not to have become seriously ill.
Parents today spoke of their shock after discovering news of the police probe, with fears the tablets brought into the school were a recreational drug.
The tablets are being analysed to determine their contents.
Police are conducting enquiries into how the tablets came into the Liverpool Road school, suspected of being brought in by a teenage boy, who is a pupil.
He is understood to be aged under 16.
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No arrests have been made.
A Merseyside Police spokesman told the ECHO: "We can confirm we are investigating following an allegation that a number of tablets were brought into Merchant Taylors school in Crosby by a pupil.
"There is no suggestion that it is widespread in the school or that anyone has become seriously ill as a result of taking one of the tablets.
"Enquiries are continuing to establish what the tablets are."
The school found the tablets on the boy and confiscated them, before reporting the matter to police.
One parent, whose child attends Merchant Taylors', said: "We are concerned that there are drugs which it appears could have been brought into the school.
"Some of the pupils watched as the police drove into the school the other day and wondered what was going on.
"It's the talk of the school at the moment."
David Wickes, headmaster at Merchant Taylors’ Boys’ School, said: "We can confirm that tablets were confiscated from a pupil in school earlier this week.
"Due to the unspecified nature of the items and the age of the pupil, we duly reported the matter to Merseyside Police, who are continuing to investigate.”
