A detainee at a detention centre near Lincoln has climbed a fence during a protest outside by campaigners.
About 50 protesters gathered outside Morton Hall Immigration Removal Centre earlier campaigning to shut it down following two deaths in two months.
A 27-year-old man from Poland was found dead on 11 January. A 49-year old inmate at the same centre died in hospital in December.
The Home Office said the centre was a vital part of the immigration system.
The detainee scaled the internal wall of the centre at about 14:30 GMT while campaigners, many from South Yorkshire and some from West Yorkshire attended the protest, which was organised by the South Yorkshire Migration and Asylum Action Group (SYMAAG).
He was still on the fence when the protesters left an hour later.
John Grayson, from SYMAAG, said the group was also campaigning against conditions inside the centre.
"We want an end to these detention centres and we think it's important to show solidarity for people in there at present."
Both deaths are being investigated by the Prisons and Probation Ombudsman.
The Unity Centre charity said detainees at the centre were "very low" and people were "sick and tired of the place".
In a statement, the Home Office said it respected "everyone's right to peaceful protest" but detention centres were "essential elements of an effective immigration system.
"Those with no right to be in the UK should return to their home country.
"We will help those who wish to leave voluntarily but when they refuse to do so, we will take steps to enforce their removal.
"All decisions to detain are taken on the individual merits of each case and for the shortest period necessary.
"We take our responsibilities towards detainees' welfare extremely seriously."
In 2014, the death of a detainee sparked a disturbance at the 392-cell centre, which opened in 2011.