An investigation is under way after the prisoners, based at HMP Kilmarnock in East Ayrshire, were admitted to hospital on Wednesday and Thursday.

A spokesperson for jail operators Serco said: "We can confirm that three prisoners from HMP Kilmarnock have been taken to hospital.

"We are in close contact with the hospital to monitor their condition."

NHS Ayrshire and Arran confirmed it was working with the prison healthcare and custody staff to investigate the circumstances surrounding the incidents.

Joanne Edwards, director of acute services, said: "We are aware of a small number of prisoners who have been admitted to University Hospital Crosshouse following suspected drug misuse.

"Due to patient confidentiality, it would be inappropriate to comment further."

Last month it was revealed that the number of drones caught flying into Scottish prisons had increased from two in 2018 to nine in the first three months of this year alone.

The remote-controlled aircraft are used to smuggle the likes of drugs and phones into jails.

The Scottish Prison Service (SPS) said it was using "all technological and intelligence tools available" to tackle the problem.

Read more:
Surge in number of drones caught flying into Scottish prisons after smuggling crackdown
Gang sentenced for using drones to drop drugs in prisons
Prisoners getting drugs and phones from drones

A crackdown on smuggling via prison letters is believed to be one of the reasons behind the recent rise in drone use.

A policy has allowed staff to photocopy letters addressed to prisoners, so inmates receive copies rather than originals.

The measure was put in place to stop drugs - in particular, benzodiazepines like Etizolam - from entering the estate by being soaked into paper.

Between August 2020 and July 2021, almost 9,000 items of mail sent to jails across Scotland tested positive for an illegal drug.

Following the introduction of the policy, drug-taking incidents dropped by 36% - from 175 in December 2021 to 112 in March 2022 - according to a letter to Holyrood's Justice Committee in May 2022 from SPS chief executive Teresa Medhurst.