The Prison Service has said it will strongly contest any legal action taken by prisoners and ex-prisoners who have had to "slop out" while in detention.
A spokesman for the service said it was made aware two months ago of about 350 prisoners who intended to sue the State because they were detained in cells that had no flush toilets.
The solicitor representing the prisoners, Mr John Devane, said he was taking the cases on the basis that their human rights had been violated.
"For prisoners who have to defecate and urinate in front of other cell mates in the middle of the night, it's very dehumanising. There is also a constitutional right to bodily integrity which is being violated."
There was also an equality issue, he said, because some prisoners did have in-cell sanitation while others did not, as well as health and safety concerns.
Mr Devane said he had 400 clients two months ago and the number had now risen to more than 800. He estimated that some 2,400 prisoners are still slopping out and more were joining the suit every day. Most of the plaintiffs are men; however, there are five women and 35 prison officers taking cases.
"The prison officers have had to endure prisoners throwing the contents of their pots at the officers when they open the cell doors in the morning."
Mr Devane said he hoped to see a case in court early in the new year.
The prisoners' claims follow a recent Scottish court action in which a prisoner was awarded £5,000.
However the spokesman for the Prison Service said this claim surrounded a very specific medical issue relating to the lack of in-cell toilets.
"In this case the prisoner claimed he had a particular medical condition, but not withstanding this he was put in a cell without in-cell sanitation and his condition was exacerbated by it."
The Prison Service had, for a number of years, been taking steps to end the practice of slopping out. All new facilities had in-cell sanitation and it was included in all refurbishment schemes.
"We are intent on vigorously defending these cases and will be mounting a fairly strong defence," he said.
He added that he was not aware of any prison officers who were taking cases. It is understood that some of the State's most notorious criminals, including the "Real IRA" director of operations, Liam Campbell, and the drug dealer, Patrick Holland, are among those seeking compensation.
