Prison officers across the North West have walked out as part of a national protest over health and safety concerns.
The Prison Officers Association (POA) said 10,000 prison workers across England and Wales are taking part in the action, which has been called as negotiations with the government broke down.
The 24 hour action began at midnight.
Labour says the Government has "lost control" of its prisons and that it has failed to tackle rising levels of violence.
Justice secretary Liz Truss said the protest is "unlawful and unjustified", according to the Prime Minister's official spokeswoman.
The government has won a High Court injunction against the industrial action.