A man staying at the Manston migrant centre has died, the Home Office said today.
The government department said a person, believed to be male, died in hospital this morning after "becoming unwell".
It is understood that he arrived in the UK as part of a small boat crossing on November 12.
He is thought to have been taken ill on Friday evening.
The Home Office wrote in a statement on Twitter: "We express our heartfelt condolences to all those affected."
A post-mortem examination is due to be carried out and the Independent Office for Police Conduct (IOPC) has been notified.
"We take the safety of those in our care extremely seriously and are profoundly saddened by this event", the statement added.
"A post-mortem examination will take place so it would not be appropriate to comment further at this time."
Inquest, the charity that provides expertise on state-related deaths, is now calling for an independent inquiry into the death.
Deborah Coles, its director, said: “It feels as if it was only a matter of time before a death like this happened in this completely closed facility.
“Notwithstanding the concerns about conditions and the impact on the mental and physical health of people staying there, an independent investigation is needed to hold the different agencies involved to account.
"Maybe this death will shock people into doing something about the Manston facility.”
It is understood that efforts to contact the man's next of kin have so far been unsuccessful, according to The Telegraph.
A Home Office spokesperson said there was "no evidence at this stage to suggest that this tragic death was caused by an infectious disease".
They added: "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."
At one point as many as 4,000 people were being detained at the site, which is designed to hold just 1,600. This number later dropped to within capacity.
Asylum seekers are meant to be at Manston for only short periods of time while undergoing security and identity checks, before being moved to the Home Office's asylum accommodation.
Some people have been held for longer periods due to a lack of alternative accommodation, with concerns raised over poor conditions.
The death comes after a diphtheria outbreak struck the migrant processing centre, with dozens of cases of the highly contagious disease confirmed in England.
The UK Health Security Agency (UKHSA) revealed that 39 diphtheria cases had been identified in asylum seekers in England this year, as of November 10, warning accommodation settings should be considered "high-risk for infectious diseases".
The Government agency said in many cases the illness had been contracted abroad and carried to the UK, stressing the need for action to "minimise the risk of further transmission".
Dr Gayatri Amirthalingam, the UKHSA's deputy director of public health programmes, said work is ongoing with the Home Office to roll out vaccines and antibiotics at Manston.
"The UKHSA has been working closely with the Home Office at the Manston reception centre where there have been a number of cases of diphtheria and other infections," she said.
"We recommend that diphtheria vaccination and antibiotics are offered to people at the centre and all those who have moved on recently.
"This is currently being operationalised and we are working with the Home Office and the NHS to make this happen."
The Home Office confirmed it was working alongside the UKHSA and NHS to provide vaccines against the disease, but stressed the number of migrants affected at Manston was "very small".
