Staff shortages at a Kent jail have led to as many as 30 inmates to each guard, a representative of prison officers has said.

It comes after a video emerged of two prisoners at HMP Elmley in Eastchurch on the Isle of Sheppey being punched in the face in a shower room.

Mike Rolfe, Prison Officers' Association representative for Kent and who also works at the site, said: "It's a very shocking, violent ritual that is taking place which troubles us as it does the general public.

"Unfortunately these things do get missed by that small amount of staff and with the cuts and reductions in front line staffing that we have faced over many years - and more recently at a faster pace - there aren't enough staff around to supervise these sorts of things to stop them from happening.”

He said the filming took place in a shower room, which prisoners are able to use when they are unlocked.

He went on to say the type of unit where the incident took place holds around 180 inmates and typically has six members of staff supervising them.

Mr Rolfe said there can sometimes be only three or four officers at a time due to sicknesses - which can often be stress-related - and the situation will only get worse as more of his colleagues are leaving and they are also struggling to recruit replacements.

He added: "Most of us joined this job to try and do something positive for society, try and rehabilitate and stop them committing crime and violence but unfortunately we find ourselves stuck with this level of violence."

He called for the support of members of the public and government ministers.

An Independent Monitoring Board report, published in April, highlighted the impact cuts were having to staffing levels at Elmley.

Police are treating the incident in the video as GBH and say enquiries are ongoing. It is believed one of the men suffered a broken jaw.

A Ministry of Justice spokesman said: "We do not tolerate violence of any kind and take swift and robust action against perpetrators."