Talks aimed at resolving a protest by dissident republican prisoners at Maghaberry prison in County Antrim have collapsed.
The prisoners said the protest was over issues including strip searching and restricted movement.
The talks have been ongoing for a month.
Mediators are expected to try to resurrect the discussions in meetings with the prison service and Justice Minister David Ford on Tuesday.
There are currently 25 prisoners in the republican wing at Maghaberry.
BBC NI home affairs correspondent Vincent Kearney said the collapse of the talks comes at a time of escalating activity by dissidents and a declaration from the government that it would not talk to any groups engaged in violence.
Prisoners have spent 23 hours a day locked in their cells since a protest at Maghaberry on Easter Sunday, when they barricaded themselves into the prison canteen, and smashed toilets in their cells.
Mediators have held a series of discussions with prisoners and the prison service over a period of three weeks.