Channel migrants are being held for up to a week in a new processing centre which is “struggling” to cope with the influx of people, a union which represents Border Force officers warned.

The POA union said the facilities at the site in Kent are inadequate, highlighting rising “tensions” which have already seen the police called and the facility run out of food and water – a claim the Home Office has denied.

Opened by the Home Office in January 2022, the Manston immigration short-term holding facility is located at the former Defence Fire Training and Development Centre in Thanet.

The union says the large number of people arriving during September means that the target of holding people at the Manston site for 24 to 48 hours is “purely aspirational”, with people staying at the facility for up to a week.

PA news agency analysis of government figures shows 7,961 people arrived in the UK after crossing the Channel in September.

POA says the facility is a “significant improvement” to the Tug Haven processing site at the Port of Dover, however they say the Manston facility is struggling to perform its role and tensions are rising.

A spokesman for the POA said: “A member working at the site likened the situation to a pressure cooker coming to the boil with a jammed release valve.

She described the ability to move people on from the site in a timely manner as that pressure release valve.

“We have had reports of incidents escalating, altercations between residents boiling over and resulting in injury with police having to be called to the site to investigate assaults and provide support to staff.

“The POA believe the failure to relieve this pressure sits at the highest level, with a Government that has not provided a coherent response at pace to the increase in numbers of migrants crossing the Channel and the strain that is putting on the facility.

“There have been days where the facility has run out of food and drinking water for residents.

“The marquees are crowded, levels of bedding on site have become inadequate, laundry facilities are inadequate, cleaning regimes are not adhered to, and issues have been raised around high levels of condensation within the marquees which has led to mould and bacteria developing.

“We will today write to Charlie Taylor, HM Chief Inspector of Prisons and urge his inspectorate to attend and assess the developing situation.”

Kent Police confirmed they had been called to the immigration centre twice in the last two weeks.

A spokesman for Kent Police said: “We attended a site in Manston Road, Manston, at around 11.55pm on September 28 to assist the Home Office following a report a small group of people were being abusive. No arrests were made.

“Kent Police attended a site in Manston Road, Manston at 8.10pm on October 2 to assist the Home Office following a report a man had thrown a plastic bottle at another man.

“A suspect was arrested on suspicion of assault and was later released on bail while enquiries continue.”

The Home Office said it was “untrue” to suggest there had been shortages of food and water at the site, insisting migrants were offered hot food, fresh clothing, toilet facilities, sanitary packs and medical care.

A spokesperson added: “The continued rise in dangerous small boat crossings is causing an unprecedented strain on our asylum system.

“Manston is resourced and equipped to process migrants securely and we will provide alternative accommodation as soon as possible.

“Despite the lies they have been sold by people smugglers, those entering the UK illegally via the Channel will not be allowed to start a new life here. These individuals will be in scope to be relocated to Rwanda under our Migration and Economic Development Partnership.”