Almost 150 inmates at a Salford prison are currently locked up for 24-hours-a day because of Covid-19.
The mother of one prisoner said she feared he will crack under the mental strain.
"They are being locked up like wild animals," she said.
Bosses at Forest Bank prison in Agecroft confirmed 147 inmates on two wings are self-isolating due to an outbreak of the virus.
The wings affected are H2 and D1.
Managers insist the prison is not subject to a major lockdown and that most men on isolated wings are still able to exercise in their 'bubbles'.
Asked if it was correct that some prisoners have been unable to shower, exercise and are eating meals in their cells, a spokesman said: "Where precautions are needed to stop spread of the virus, isolation is an option."
Asked if it was true that a number of prisoners are in their cells 24-hours-a day, the spokesman said: "Yes. Where precautions need to be taken, we will to stop the spread of the virus. This has meant 147 prisoners isolating across the two wings."
Social visits at the prison have been stopped. The restrictions are to be reviewed on October 26.
The prison, which is run by Sodexo Prison Services, has capacity for 1,460 inmates.
Matt Spencer, director at the prison, said: "A small number of staff and prisoners at HMP Forest Bank hace tested positive for Covid-19.
"We are currently working with Public Health England and the local authority to reduce transmission of the infection, including ensuring appropriate self-isolation and testing takes place.
"A number of measures have been put in place to prevent any spread of the virus, including restricting visits and the necessary PPE for staff. All restrictions remain under constant review."
The mother of one prisoner said: "My son is currently serving a sentence in there.
"Surely this is no good to their mental health.
"I have spoken to my son on the phone and he broke down. The pressure is getting to him. I know he and others have done bad things and have to serve the time, but locking someone up in a room the size of a bedroom 24-hours-a day cannot be right.
"They are being locked up like wild animals."
A Prison Service spokesperson said: "The measures we put in place limited the spread of the virus and saved lives.
"In line with the latest advice from Public Health England we are gradually easing restrictions, including increasing time out of cells."
