Failed asylum seekers at a Lincolnshire immigration centre say they have begun a hunger strike.
Police said they were monitoring the situation at the former women's prison, Morton Hall near Lincoln.
The UK Border Agency said a sit-down protest, involving around 18 Afghan nationals, started at about 09:00 BST.
Protester Mohammad Nadi Mengal said the men had gone on hunger strike because they did not want to be sent back to Afghanistan.
'No food, no water'
"We left Afghanistan about eight year ago, nine year ago, 10 year ago. Our country is not safe," he said.
"No food, no water, we've been sitting down here since last night. We don't want to eat the food or anything, we just sit here."
The UK Border Agency said officials would be talking to the men.
Alan Kittle, the agency's director of detention services, said: "We are aware of a peaceful protest at Morton Hall immigration removal centre involving Afghan detainees.
"The UK Border Agency only ever returns those who both the agency and the courts are satisfied do not need our protection and refuse to leave voluntarily."