Prison staff in England and Wales have been urged to take “protest action” over violence and safety concerns, the Prison Officers’ Association has said.
Steve Gillan, POA general secretary, called for union members to protest outside their work from 07:00 BST on Friday until “instructed otherwise”.
There was “unprecedented levels of violence” behind bars, the union said.
It comes after an inspection report on Thursday found inmates had effectively taken control at HMP Bedford.
BBC home affairs correspondent Danny Shaw said industrial action by prison officers is illegal so the “walkout may not last long”.
The POA accused the government of overseeing “the demise of the prison service over the last eight years.”
In a statement, Mr Gillan said the government had been “paying lip service” to safety and human rights of prison staff.
“We will now be demanding that the government provide safe prisons, meet our demands to improve personal protective equipment, reduce levels of violence and overcrowding,” he added.
The union said the decision to call for a protest followed a letter from the chief inspector of prisons, issuing an urgent notification notice at HMP Bedford, published on Thursday.
Inspectors said they found HMP Bedford prisoners regularly ignored rules, that there was a smell of drugs “pervading” some wings and an infestation of rats.
Peter Clarke, the chief inspector of prisons, sent a letter to Justice Secretary David Gauke, which means the government has to publish a response and plan of action for the jail within 28 days.
It is the fourth jail to be subject to the “urgent notification” process after Nottingham, Exeter and Birmingham.