The walkout by prison officers in most jails is unlawful and ministers are considering court action to end the dispute, the Government said today.
The Ministry of Justice said ministers could seek an injunction to force staff to return to work.
Prison officers started unannounced 'protest meetings' outside of their workplace at 7 am this morning. They are protesting over government plans to link their normal pension age to the state pension age.
More top news
At least 14 people have been killed after an overcrowded bus slipped off a mountain road and fell 980ft in Nepal.
A man in his 70s has been arrested on suspicion of the murder of Elsie Frost more than 50 years ago.
A challenge to the decision not to take further action against Sir Cliff Richard over alleged sex offences has been dismissed.