HMP Ranby was described as "in crisis" by the Chief Inspector of Prisons Nick Hardwick after a critical report was released about the institution.
Following an unannounced 11-day inspection by HM Inspectorate of Prisons in March, the report found two prisoners died through "self-inflicted deaths" last year, and a further two have died in a similar way since then.
Conditions in part of the prison, which holds more than 1,000 men, were described as dirty and prisoners were found to have climbed netting in a bid to force a transfer to another facility.
Nearly half the population said they had felt unsafe having been victimised or intimidated, findings showed.
Evidence was also found of an increasing number of incidences of self-harm at the category C training prison, and the availability of legal highs was also found to have increased.
Chief Inspector of Prisons Nick Hardwick said the report showed a prison "in crisis".
More top news
The squalid conditions in Calais shanty towns, nicknamed 'The Jungle', where migrants stay who are desperate to get to the UK.
An emergency call handler who hung up on a frantic caller as she tried to save her dying friend's life has resigned.
Suspected plane debris which has washed up off the east coast of Africa may be tested to see if it has any link to the downed MH370 plane.