Prisons have seen staff numbers increase by an average of 15% in the last year as part of a national recruitment drive to tackle rising violence in jails.

In total, 120 extra prison officers and 27 operational workers were recruited in Sheppey, Home Office figures show.

HMP Elmley saw the most significant rise, with its workforce bolstered by 21% in the 12 months to December - the equivalent of 82 more members of staff.

It brings the total number of full-time workers to 473. A further nine were due to begin Prison Officer Entry Level Training between January and April.

At Swaleside Prison there were 474 full-time members at the end of last year - 55 more than in 2017, an increase of 13%.

A further 17 staff members were poised to begin training. And at Standford Hill, 10 more workers were recruited - an eight per cent rise.

Deaths, violence and self-harm cases hit record levels in England and Wales’s prisons during the first nine months of 2018.

Frances Crook, chief executive of the Howard League for Penal Reform, said: “Ministers have rightly identified that we must ease pressure on the prison system, and the rising levels of violence and self-injury behind bars show why change is so urgently needed.

“A larger, and refreshed, workforce ought to have a positive impact in the long run but, ultimately, reducing the number of prisoners is the key to protecting staff, saving lives and making the public safer.”

The Ministry of Justice is investing £70m in improving safety and security in jails. A spokesman said 4,300 additional prison officers has been recruited nationwide since October 2016.

Justice Secretary David Gauke said: “Violence and self-harm in our prisons is unacceptably high and these figures underline why we are spending an extra £70 million to fight the drugs plaguing prisons and boost security, while also training over 4,000 new prison officers in handling the complex offender population.

“Clearly there is huge amount yet to be done but I am determined to cut the violence so prisons can focus on rehabilitating the offenders who will be back out at some point.

“I am optimistic that the measures we have been putting in place will help us to reduce violence and ultimately better protect the public.”