Manston is designed to hold arrivals in the UK for 24 hours, but some migrants were reportedly held there for up to 32 days amid a backlog in the processing of asylum applications.
The backlog has been exacerbated by an increased number of asylum applications, antiquated IT systems, high staff turn-over, and too few staff, according to a report by Parliament’s Home Affairs Committee.
An official inspection of the centre in July found that “the length of detention was far too long, often more than 24 hours and sometimes far in excess of this”.
Suella Braverman, the Home Secretary, began an operation to remove occupants of the centre and move them into hotels, which costs the taxpayer an estimated £7 million per day.
The Home Office is facing two legal challenges over the centre, from a woman detained there and from the PCS – a union representing Border Force workers.
Ms Braverman was reportedly given legal advice that the length some migrants had been held in the detention centre was in breach of the law.
She has denied that she “ignored” advice and says she did not “veto” it, but does not deny receiving it.
A Home Office spokesman said: “We can confirm a person staying at Manston has died this morning in hospital after becoming unwell. We wish to express our heartfelt condolences to all those affected.
“Until a post-mortem examination takes place we cannot comment in detail, but there is no evidence at this stage to suggest that this tragic death was caused by an infectious disease.
“We take the safety and welfare of those in our care extremely seriously and provide 24/7 health facilities with trained medical staff at Manston.”
Yvette Cooper, the shadow home secretary, said there would need to be a “full investigation” into the incident.
Enver Solomon, chief executive of the Refugee Council, said: “Every person in Manston must be looked after with the care and attention they need. When a tragic death like this takes place it is always a matter of serious concern.
“It is vital that a thorough and speedy investigation takes place to understand what happened and whether all the necessary procedures were followed.”