Hundreds of riot police were called in last night to take over Northern Ireland's jails.
They were ordered in after prison officers refused to go back on duty in the latest stage of a bitter dispute over security packages for colleagues facing terrorist threats. Specialist units trained to deal with sectarian street disorder have been deployed, security sources said. "This has the potential to tie up hundreds of police officers."
All visits to Maghaberry Prison near Lisburn, Co Antrim, were cancelled. Magilligan in Co Derry and the Hydebank Young Offenders' Centre near Bangor, Co Down, were also affected.
Mr Peter Russell, director general of the Northern Ireland Prison Service, said: "This action is reprehensible. It increases the potential for disruption in the prisons when there is already a volatile atmosphere."
More than 1,600 officers manage the three prisons, and sources said at least 60 per cent of the 500 on duty yesterday did not return from lunch.
Management and staff at the three prisons have been in a deepening row ever since officers' details were allegedly stolen by the IRA at Stormont last year. Loyalist and dissident republican groups have also carried out bomb attacks on officers' homes.
Tensions heightened further when so-called dirty protests at Magilligan led the authorities to begin segregation of the rival paramilitary factions. A pay dispute and plans to bring in civilian staff to help with the segregation also strained relations.
Mr Finlay Spratt, of the Prison Officers' Association, said he knew nothing in advance about the action. But he said: "I fully support any decision they have made.
"If they are stressed out and sick they have my utmost sympathy. This was to show government and management that they had had enough."
However, Mr Russell claimed union representatives were involved. "I regard this as unofficial industrial action. It is simply not credible for the POA to suggest that this is unilateral action taken by prison officers without their approval." - (PA)