The UK government took the unusual step of launching a High Court bid to block industrial action after guards gathered outside establishments around the country.
Granting an injunction, Mr Justice Kerr said it was a “very urgent” application with evidence of up to 80 per cent of staff taking some sort of action in the majority of prisons.
“A number of incidents have occurred in prisons today and the situation is very concerning indeed,” the judge added.
The Prison Officers Association (POA) directed members to protest yesterday after talks with the government over health and safety concerns broke down.
Courts were hit by disruption as a result.
At the Old Bailey, the trial of Thomas Mair, who denies murdering MP Jo Cox, was brought to a halt due to the action, with the case adjourned until today.
Elsewhere, a planned appearance of prison governors at the Commons Justice Committee on Tuesday morning had to be postponed.
Prison officers are effectively banned from going on strike and the move was branded “unlawful” by Justice Secretary Liz Truss.
Answering an urgent question in the House of Commons, she said she met the POA on 2 November and talks with her team over safety measures continued over the next fortnight.
“These talks were due to continue this morning,” Ms Truss told MPs. “Instead the POA failed to respond to our proposals and called this unlawful action.”
Ms Truss said the union’s position is “unnecessary and unlawful” and “will make the situation in our prisons more dangerous”.
Up to 10,000 staff joined the protest after a string of high profile incidents at prisons, including an alleged murder, a riot and the escape of two inmates.
Two prisoners escaped from Pentonville prison in north London earlier this month, sparking a manhunt after which they were eventually recaptured.
Weeks earlier, inmate Jamal Mahmoud, 21, died after being stabbed at the jail on 18 October in an attack which left two others injured. And on 6 November, up to 200 prisoners went on a rampage in HMP Bedford.
Announcing the move, the union said the “continued surge in violence and unprecedented levels of suicide and acts of self harm”, coupled with the recent alleged murder and escapes “demonstrate that the service is in meltdown”.
About 60 guards gathered in the car park within the gates of Pentonville. Dave Todd, POA representative for London, Kent, Surrey and Sussex, said conditions in prisons were “volatile and dangerous”.
He said: “It’s just unsafe. Prison officers taking this type of action speaks volumes.”