Three HMP Liverpool guards were taken to hospital with one suffering a reported broken eye socket when violence broke out at the Walton facility.
The Ministry of Justice has launched an investigation into the assaults, which were on male guards and happened at about 11am on Monday (5 January).
Prisons Minister Andrew Selous told the Liverpool Daily Echo the violence was "abhorrent".
"This kind of violence against our hardworking prison officers is abhorrent and unacceptable, and my thoughts are with these staff members and their families," Selous said.
"I have been clear that violence in our prisons will not be tolerated which is why we have been working closely with the police and Crown Prosecution Service to ensure that prisoners who attack our staff are prosecuted and spend longer behind bars."
HMP Liverpool was constructed in 1855 and covers some 22 acres. It has a single capped security wall and there are eight wings.
It is a standard prison, which means it keeps suspected criminals either on remand or awaiting trial as well as inmates who have been convicted.
A spokesman for Merseyside Police said: "Merseyside Police can confirm that a full investigation is under way following a report of an assault on three prison officers at HMP Liverpool on Monday, 5 January."