HMP Birmingham faces continued drugs problem
A new report from Birmingham Prison's monitoring board has said the atmosphere at the jail is improving, but that drugs remain a problem.
HMP Birmingham became the first in the UK to be privatised when it was taken over by G4S in October 2011.
A report by the Chief Inspector of Prisons in June 2012 highlighted problems with drugs.
The latest independent monitoring board report found almost 20% of inmates had tested positive for banned substances.
A G4S spokesperson said the company was pleased progress in some areas had been identified but accepted "there remain areas where there is room for improvement".
The latest report found a net designed to stop drugs and mobile phones being thrown into the prison was not replaced after damage last winter.
The report added: "Unfortunately the location of the prison right next to busy roads makes it easy for people to throw packages over the walls."
Other concerns highlighted in the report included the number of sex offenders and category D prisoners at HMP Birmingham, despite not being the most appropriate place for these inmates.
The board additionally found foreign national prisoners were being retained "long after their sentence expiry date".