Inspectors discovered rats running along corridors when the visited a jail on the Isle of Sheppey.

During an unannounced inspection at Swaleside Prison in December they saw the rodents near rubbish bags.

Peter Clarke, HM Chief Inspector of Prisons, said: "During our night visit we saw rats in corridors near rubbish bags that had not been disposed of correctly.

Scroll down for video

"There was an excessive number of prisoners supposedly employed to clean but the lack of effective staff supervision resulted in little cleaning actually taking place.”

In his report, published today, he praised the Category B jail, which houses 1,112 men at Eastchurch, for becoming "safer and more respectful" since its last inspection in 2016 when it was described as "dangerous" and safety was assessed as "poor."

But he added it had also become weaker on activity and rehabilitation during the past two years and still suffered high levels of violence and too many men felt unsafe.

He said Swaleside remained an "unquestionably a difficult place to run and an institution that presents many risks” but said there had been good work to reduce the supply of drugs, a significant effort to improve safety and some 'impressive' care for those at risk of self-harm.

WATCH: Concerns earlier voiced about rising violence at HMP Swaleside

The overall assessment for safety rose from "poor" to "not sufficiently good."

He said progress had been “lop-sided” with rehabilitation and resettlement work now poor, the lowest assessment.

He found relationships between staff and prisoners were generally good with more than 70% of men saying staff treated them with respect.

But many staff were inexperienced with 35% in the job for less than a year and some lacked confidence to challenge poor behaviour.

Inspectors found 32% of men were locked in their cells during the day, an improvement on 2016 but still poor.

Good standards of work were evident in education, skills and work and, for those engaged, the achievement of qualifications was high.

But there was a poor allocation to activity, under-employment, poor attendance and poor punctuality.

Mr Clarke added: “The core tasks of a prison which manages this type of prisoner are meaningful sentence management, the reduction of risk of harm and ultimately the protection of the public.

"In these tasks Swaleside was failing badly.”

Public protection was weak and offending behaviour interventions were limited, especially for the prison’s population of sexual offenders.

More than 160 men convicted of sex offences were moved to Swaleside at the end of 2016 in an attempt to stabilise the jail.

Overall, Mr Clarke said: "There was much to commend at Swaleside.

"Managers were energetic, caring and innovative, and staff, though inexperienced, were proactive and helpful.

"Improvements were clearly to be seen, as reflected in our assessments.

"That said, many improvements were undermined by failings elsewhere.

"While there had been some incremental improvements in safety, many prisoners were not fully engaged in the regime and some prisoners’ rehabilitation needs were not being met.

"Managers need to take a step back and think carefully about how they will not only sustain and integrate their achievements but also take a holistic approach to improving outcomes across all four of our assessments.”

Phil Copple, Director General of Prisons at the HM Prison and Probation Service, said: "I am pleased inspectors recognise the improvements that have been made, along with the energy and care that Swaleside staff put into what is acknowledged as their particularly challenging work.

"Clearly more still needs to be done to address violence and give prisoners more time out of their cells in education and training.

"Improved safety procedures have been introduced and the prison will also benefit from the new education framework we have implemented across the country to help offenders use their time in custody constructively.”

Swaleside was opened in 1988 and holds lifers, sex-offenders and prisoners with personality disorders and challenging behaviour. Three-quarters have a high risk of harm and 60% had committed a violent offence.

Nearly 200 were employed as wing workers but 287 prisoners, about a quarter, remained unemployed.

Governor Mark Icke said: "The report from the Chief Inspector demonstrates the progress being made by my team and the Residents at HMP Swaleside against the four healthy tests.

"One area I was really pleased the inspection team noticed improvement in was safety.

"During our night visit we saw rats in corridors near rubbish bags that had not been disposed of correctly" - Peter Clarke, HM Chief Inspector of Prisons

"I do recognise that further work is required to embed some of the newer initiatives introduced to reduce violence but I am confident that the whole prison approach will achieve this and is showing early signs of improvement.

"I also pride myself on Swaleside being a respectful place to work and live. Again, the Chief Inspector recognised this area of improvement."

He added: "The staffing position has improved and we have seen an increase in staff in post at Swaleside.

"This, of course, means a large number of my staff are relatively junior in service but my management team is ensuring new staff are being developed and retained.

"The outcome for rehabilitation and release was disappointing and it is acknowledged that further work is required to drive positive outcomes in this area along with a number of our partners.

"Overall, the findings demonstrate the distance travelled since their previous inspection."

Inside Swaleside Prison: a special report