A member of staff at HMP Nottingham has tested positive for coronavirus.
The category B men's prison, which has around 800 inmates, is based in Perry Road in Sherwood.
The independent monitoring board for HMP Nottingham, which monitors the welfare of prisoners, confirmed there had been a Covid-19 case.
HMP Nottingham also sent out a tweet informing the public it was the prison's first case.
Janet White, chair of the independent monitoring board at HMP Nottingham, said: "They had their first known case confirmed today (Tuesday, April 14).
"It is a member of staff. We were notified as a matter of cause when there is anything significant happening within the prison.
"They have got lots of measures in place, which we have been made aware of and keeping an eye on.
"It is advice given by Public Health and the NHS."
The role of the member of staff at HMP Nottingham has not been disclosed.
A tweet from HMP Nottingham's Twitter account said: "First C-19 confirmed case on a member of staff today.
"They had no symptoms and this remains the case.
"However, a test has confirmed positive. Undoubtedly they'll have had contact with others.
"Staff and prisoners advised to maintain hygiene standards. No other confirmed cases presently."
Nottinghamshire Live contacted The Ministry of Justice, which manages HMP Nottingham, but it would not comment on individual prisons.
A spokeswoman said: "We have robust and flexible plans in place keep prisoners, staff and the wider public safe based on the latest advice from Public Health England."
