Housing asylum-seekers on the Bibby Stockholm “floating prison” would be “inhumane” and risks “retraumatising” people who have escaped war zones and other “horrors”, the leader of a refugee charity has warned.

Steve Smith, the CEO of Care4Calais, also expressed his fear that the barge being prepared to accommodate more than 500 refugees at Portland, Dorset, is an “accident waiting to happen” because of insufficient fire safety on board with the Government putting money as a “higher priority than people’s lives”.

Mr Smith said that the charity is currently assisting 11 people who have received letters from the Home Office advising them that they will be moved to the vessel.

The letter states: “You are not being detained under immigration powers, and this is not detention accommodation. You are free to leave the site, but we would request that you sign in and out of the site when you leave and return, so we can assure your safety.”

It adds that facilities on board will include an on-site nurse, recreational space, voluntary sector activities, English classes, entertainment areas, worship room, private space for consultations and to make phone calls and wifi access.

The Government has said there is “no timeframe” for the arrival of the first refugees to the Bibby Stockholm while final safety checks are being carried out.

Mr Smith told the PA news agency: “The obvious fire hazard of moving a large number of people across to the Bibby is clearly causing a delay.

“We know the Bibby barge was intended for 220 people, we know the intent is to put 506 residents aboard but, by the time you add security staff and other staff, that would come to 546.

“Now you have a barge with narrow corridors with three decks, with terms of crowding people in into what were originally single person rooms with two and in some of the larger rooms up to six, doubling those on board.

“If you’re on the far side of this barge and on the upper storey and there are only two fire escapes and that’s where you are when a fire breaks out, you can imagine the absolute chaos and pandemonium as panicked individuals crammed in narrow corridors try to get out.

“They are not able to escape on the water side and if they do, what if they can’t swim, jumping into the water without lifejackets.

“This is an absolute accident waiting to happen, it looks like the Government is prepared to save money, making it a higher priority than people’s lives.”

He added “Amongst those we are supporting are the survivors of torture, people with disabilities and people who have experienced trauma at sea.

“Housing any human on a ‘floating prison’ like the Bibby Stockholm is unacceptable. Doing so to people like this is completely inhumane.”

He continued: “Our concern in many cases, probably most cases, is that these will be individuals who have crossed the Channel in flimsy boats and they don’t do this for fun.

“They will have probably had a fairly terrifying journey from the place of origin which could be something like Afghanistan where, having survived the war, perhaps having fought on the side of British troops there.

“Individuals like that who have been through all these horrors have been through unwelcoming and sometimes hostile countries like the Balkans and Libya to get to Calais, sleeping rough, braving the Channel under really difficult circumstances and then to be put further on a boat, this has all the potential for re-traumatising.”

Mr Smith said that speeding up the asylum process by prioritising those from high-risk countries such as Afghanistan and providing a safe passage system similar to that put into place for Ukraine would reduce the need for centres like the Bibby Stockholm.

He said: “What can we do? Speed up asylum claims process, clear the backlog, provide safe passage, allow people to start working and integrate better into the community and then concerns about it costing us £6 million a day start to dissipate.”