Delays in fixing broken prison windows is making it easier for drones to be used to deliver drugs and weapons, a report has warned.

Findings published on Wednesday laid bare the state of “crumbling” jails in England and Wales.

This included a catalogue of “appalling” conditions such as widespread rat infestations and floods of raw sewage.

The details from Independent Monitoring Boards (IMB) – made up of volunteers tasked by ministers with scrutinising conditions in custody – have prompted concerns that the prison environment could be contributing to reoffending rates and hindering inmates reforming.

This is a very concerning report that once again highlights the shocking extent of the prison crisis we inherited

Delayed maintenance and repairs had “serious safety implications at many prisons”, with broken windows and grilles meaning there was an “increased the risk of illicit items being smuggled into the prison”, the report said.

Delays in broken windows being replaced were making it easier in several jails for “drones to deliver items such as drugs and weapons to the prison”, according to the findings.

An “urgent” investigation to replace 800 insecure windows and sets of bars was launched after a prisoner was thought to have been killed by a weapon believed to have been smuggled in through a window at HMP Pentonville in 2016 and two inmates escaped through a cell window afterwards, but is yet to be completed eight years on.

It comes after the prisons watchdog likened high security jail HMP Garth near Lancashire to an “airport” because there were so many drones flying in drugs.

Chief inspector of prisons Charlie Taylor also reportedly warned the surge in activity could see guns smuggled into jails dogged by drug gang wars.

The IMB report detailed a string of other problems, including:

– “Acute” problems with vermin, with rat infestations being a common issue, as well as cockroaches, biting flies infesting showers, dead rodents rotting on the wings, and cells taken out of use due to bedbugs.

– Inmates being bitten by “venomous false widow spiders” at HMP Bullingdon, near Oxford, although jail officials attributed this to disturbance caused by renovation work rather than a lack of cleanliness.

– Suspected raw sewage leaking through several ceilings in one prison and gathering in pools on the floor in another.

– Concerns that there were delays in acting on information suggesting radon gas was present in HMP Dartmoor, prompting fears that staff and inmates could have been exposed to “significant safety risks”.

IMB national chairwoman Elisabeth Davies said the findings paint a “stark picture” of the “crumbling prison estate” and highlight the “consequences of underinvestment and sticking-plaster solutions”, with prisoners expected to be reformed and rehabilitated in “appalling” conditions.

“It should serve as a warning against continuing down these paths”, she added.

The Prison Service is “barely able to cope” when jail spaces are taken out of action unexpectedly amid “decades of underinvestment”, she said.

The “inefficient spend” of the little money available is as problematic as the lack of investment, Ms Davies added as she highlighted examples of “huge investments in repairs and new facilities” which have later been found to be “unfit for purpose, or simply sit unused”.

Governors have “far too little autonomy” to find the “most cost-effective and speedy solutions” for the prisons they run and often feel hamstrung by purchasing systems and other obstacles, while “bureaucracy and red tape prevails over common sense”, she said.

Despite finding “extremely unhygienic, and occasionally dangerous, conditions”, Ms Davies added there was “little accountability when maintenance providers’ performance fell short”.

Rob Preece, from charity the Howard League for Penal Reform, said the report was further evidence of the “urgent need for change in the prison system”, adding: “Instead of wasting billions on building new jails, we should focus our attention on fixing the problems in the ones we already have.”

Campbell Robb, chief executive of social justice charity Nacro, said the “abhorrent conditions… should have no place in a modern prison system”.

“We are concerned that such environments undermine the delivery of vital rehabilitation work to reduce reoffending and drive down crime”, he added.

“It’s imperative that the Government recognises the interconnection between the environment in prison and the success of measures designed to reduce crime.”

Prisons minister Lord Timpson said: “This is a very concerning report that once again highlights the shocking extent of the prison crisis we inherited.

“The Government has already taken immediate action to address the crowding chaos engulfing our jails. We are now focusing on improving conditions in the long term so our prisons create better citizens, not better criminals.”