A Nigerian believed to be in his forties has died in a detention centre in the United Kingdom.

The immigration detainee, who is yet to be named, was found dead on Thursday evening in his cell in Colnbrook Immigration Removal Centre.

The UK’s Home Office is investigating the incident, The Independent reports.

Another detainee, Tapiwa Furumdi, 24, who has been in the facility for a year, was said to have discovered the victim lying still in his cell.

“Someone had gone into the room and found a body and started making noise. Apparently he was already dead. I heard something like: ‘This bloody immigration, look what they’re doing to us,’” he said.

“When I looked in the room, his tongue looked all bloated out of his mouth. I’m still shaken up by it.”

A Home Office spokesperson said the UK government condoles with the victim’s family and friends.

Human rights campaigners have long called for a 28-day limit for detention in removal centres, saying the system is severely damaging for the wellbeing of detainees.