Government neglect has "directly contributed" to an alarming rise in violence and drugs at one of the country's oldest and busiest prisons, it is claimed.
The Independent Monitoring Board at HMP Pentonville has called on ministers to provide "adequate funds" for urgent improvements.
It asked Justice Secretary Robert Buckland and prisons minister Lucy Frazer to visit the prison so they could see the conditions for themselves.
The concerns have been raised a week after chief inspector of prisons Peter Clarke warned violence fuelled by gangs, drugs, debt and volatile young prisoners have "increased markedly" at the north London jail.
Violence has shot up by more than 50 per cent since 2017, according to Mr Clarke's report.
In the last six months there have been 264 assaults on staff and inmates and 61 fights, compared with 196 and 65 respectively during a previous inspection, it found.
In March four officers and around 40 prisoners were attacked each week while "Improvised weapons" are being found on an almost daily basis, the IMB said.
It called for more funds for equipment to tackle drugs and carry out searches while the age of the prison made it impossible to instal a full body scanner, the report said.
IMB chairman Camilla Poulton said: "Neither Her Majesty's Prison and Probation Service nor the Ministry of Justice have given Pentonville the money, care and scrutiny that it needs for years, in the IMB's opinion.
"An audit revealed that less than half of the skilled Government Facilities Services Limited (formerly Carillion) workforce required to maintain the building to health and safety standards were in place.
"Other audits, commissioned by the new governor after arriving in August 2018, revealed shortfalls relating to safety, use of force and other issues.
"The board believes this neglect directly contributed to the violence, drugs and self-harm."
The Victorian jail's four wings - which are largely unchanged since it was built in 1842 - now hold up to 1,310 adult men, with nearly 10% being under 21.
There are around 33,000 "movements" through the category B prison's reception every year - making it the busiest in the country, inspectors previously said.
The prison lacked the staff it needed for most of the year, according to the board. But it acknowledged new officers were "doing their best for prisoners".
Reported incidents of self-harm have increased this year from 500 to 598, the report also found.
The IMB also raised concerns about the prevalence of insecticide-resistant cockroaches and mouldy, broken showers.
It said: "Whilst other London prisons have benefited in recent years from additional resources, Pentonville has not.
"It desperately needs money now to raise the standard of day-to-day life for prisoners and staff and deliver its dual function of serving local courts and helping prisoners lead productive lives."
IMBs are made up of volunteers appointed by justice ministers to scrutinise prison conditions.
The Ministry of Justice has been contacted for comment
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