Birmingham Prison in Winson Green is dogged by overcrowding and serious drugs problems, including packages being thrown over the walls to inmates, a report has revealed.

Nick Hardwick, Chief Inspector of Prisons said that HMP Birmingham, now run by private company G4S, had shown improvements in some areas and was “safer”.

But serious concerns were raised about the drugs problem, including high rates of positive tests, highlighting how many illegal substances were getting into the prison.

In just one three month period prior to the inspection 54 “throw over” packages had been intercepted by prison guards in the exercise yard, but many more will have got through.

In spite of this, no netting was installed to prevent it happening. G4S told the Birmingham Post that this was now being installed.

Overall 42 per cent of inmates said they felt unsafe, and figures showed there were 23 assaults and 11 fights each month.

Mr Hardwick said: “Birmingham prison has recently made some relatively simple but nonetheless important improvements but the prison also has a number of significant strategic challenges it needs to resolve. It is a cleaner, safer and more decent place. However, first night and vulnerable prisoner arrangements are significant exceptions to that overall picture.

“Two important areas of the prison – purposeful activity and resettlement – are weak and a determined strategic effort is required to improve them.”

HMP Birmingham was the first public sector prison to be taken over by a private company, and the inspectors found there had been progress in some areas.

The report said: “HMP Birmingham is in many ways a typical, inner-city local prison on a largely Victorian site. It holds the same sort of short-stay adult men with the wide range of needs and challenges that you would find in almost any local prison.

“What makes it untypical is that in October 2011, three months before this inspection, amid some controversy, it became the first public sector prison to transfer to the private sector. HMP Birmingham is now run by G4S.”

The inspectors said it was too early to judge if the transfer to a private company had been successful, but there were some signs of improvement.

These included the use of force to restrain inmates had “dropped significantly” since the last inspection, fewer inmates were put into seclusion and that overall the prison was “reasonably safe”.

But the inspectors found there were “important exceptions” to the steps forward, including weak strategies to tackle bullying inside.

Mr Hardwick said he had overheard prisoners bragging about how easy it was to get illegal substances past the guards: “There was a high rate of positive drug tests and as I walked past an exercise yard close to a road, prisoners joked how easy it was to throw drugs over the wall into the yard. This was indeed a regular occurrence.