THE Independent Police Complaints Commission (IPCC) is investigating after a man fell ill whilst being held in custody by Gwent Police.
The force itself referred the case - involving a 31-year-old man currently in hospital with a serious head injury - to the IPCC.
The man was involved in an incident near the Wong Chinese takeaway on Blackwood Road, Pontllanfraith, at around 7.45pm on Saturday September 22.
He remains at the University Hospital of Wales, Cardiff.
"Following a referral from Gwent Police, the IPCC has commenced an independent investigation after a 31-year-old man was taken ill in custody at Ystrad Mynach police station on Sunday September 23," said an IPCC spokesman.
"Gwent Police were called to Nevill Hall hospital at 12.10am, to reports by hospital staff of disorderly behaviour. The man, who had been admitted the previous evening with a head injury, was arrested and taken to Ystrad Mynach police station.
"At around 7.50am, officers called for an ambulance after the man became unwell and he was taken to hospital where he remains.
"The IPCC investigation is at an early stage and we will release further information in due course."