An investigation has been launched at an immigration removal centre after a detainee died.
Inmates at Haslar rioted in 2003
First aid staff tried to revive the collapsed inmate at Haslar detention centre in Gosport but failed.
The Home Office said the death was probably from natural causes, but a post mortem would follow and a full investigation by the prisons ombudsman.
The Hampshire centre was the scene of riots and breakouts in 2003 and was criticised by prison inspectors.
Emergency services were called to the centre just before 1500 BST on Saturday, but the detainee was pronounced dead at 1550 BST.
'Matter of regret'
The inmate's name will not be released until their next of kin have been informed.
The Home Office spokesman said: "The death is suspected to be due to natural causes."
Haslar has a health centre on site for the care of its detainees.
The detention centre was the scene of riots in September 2003 in which an officer was injured and £2,000 worth of damage was caused.
Last August four asylum seekers went on the run from the centre.
And earlier in the year several inmates started a brief hunger strike in protest at being kept in what they claimed were bad conditions.