A Polish man has died while being detained at an immigration removal centre.
The 27-year-old was found dead on Wednesday at Morton Hall, in the village of Swinderby, near Lincoln.
The Home Office said an investigation is being carried out.
A spokesman said: "We can confirm that a 27-year-old Polish man who was detained at Morton Hall immigration removal centre was found dead on Wednesday 11 January. Our thoughts are with the individual's family at this very sad time.
"As is the case with any death in detention, the police have been informed and a full independent investigation will be conducted by the Prisons and Probation Ombudsman."
The Unity Centre charity said the man, who they described as "young and caring", had killed himself.
A charity spokesman said: "He spent his time watching TV, playing games and at the gym. They (detainees) say the vibes at the centre are 'very low and people are sick and tired of the place'."
Morton Hall is run by the Prison Service on behalf of UK Border Agency. It has 392 rooms spread across six residential units, and holds adult men.
The centre is used to detain some asylum seekers who are awaiting decisions and also people whose asylum claims have failed are awaiting deportation.
Some, like Morton Hall, are run directly by the Prison Service but others are run under contract by private companies.