There were “fundamental failures” over housing asylum seekers in military barracks, parts of which were “filthy”, inspectors found.

At Napier Barracks in Kent, people at high risk of self-harm were found in a “decrepit” so-called isolation block that was “unfit for habitation”.

The findings, published on Monday, follow inspections by the Independent Chief Inspector of Borders and Immigration (ICIBI) and Her Majesty’s Inspectorate of Prisons (HMIP).

The Home Office has faced repeated criticism over its use of Napier Barracks in Folkestone and Penally Camp in Wales to accommodate asylum seekers.

However, Home Secretary Priti Patel and immigration minister Chris Philp have both previously defended the use of such sites.

On Monday evening, the department repeated its assertion that “it is wrong to say it is not adequate for asylum seekers”.

The findings were published on the same day 115 people, including women and children, were brought ashore in Dover after crossing the Channel – the most of any day this year.

Inspectors said: “The environment at both sites, especially Napier, was impoverished, run-down and unsuitable for long-term accommodation.”

At the Kent site, residents who may have been children were also housed in the same block pending an age assessment, in one case reportedly for up to two weeks, the inspectors said.

At both locations, residents described feeling trapped in poor conditions and feared that if they moved out they would jeopardise their only source of support and possibly their asylum cases.

Inspectors added: “We met many men who described feeling depressed and hopeless at their circumstances. In our resident survey, all of those who responded at Napier and the vast majority at Penally said they had felt depressed at some points.

“At both sites about a third of respondents said they had mental health problems; about a third of respondents at Napier said they had felt suicidal.”

Residents at both locations reported being shouted at and intimidated by protesters and members of the public who did not want them there.

Health concerns over Covid-19 were also addressed in the inspectors’ findings, particularly around warnings from Public Health England and Public Health Wales.

Inspectors said: “Given the cramped communal conditions and unworkable cohorting at Napier, once one person was infected a large-scale outbreak was virtually inevitable.”

Also in the findings was that the Home Office gave its accommodation contractors less than two weeks to make each site operational.

Responding to the inspectors’ comments, the Home Office said it had told the provider that runs the sites to put in place a robust plan to improve the services, and improvements were being made.

Reacting to the findings, Detention Action director Bella Sankey said: “This is the sort of report that should make decent people consider their positions.”

She called for the barracks to be closed immediately and for “those responsible fully held to account”.

Yvette Cooper MP, chair of the Home Affairs Select Committee, said: “At a time when the Home Secretary and Permanent Secretary have told us they are making major changes to improve the culture and the humanity of the department in response to the Wendy Williams Windrush review, this report shows they haven’t yet learnt the lessons.”

Naomi Phillips, director of policy and advocacy at British Red Cross, said: “These sites are completely inappropriate and inhumane as housing for people fleeing war, persecution and violence.

“The people we’ve spoken to in Penally have told us that they didn’t receive health screenings, were given little or no information about what was happening to them, and simply do not feel safe in the barracks.

“Our worst fears about the impact on people’s mental health have been realised.”

The publication of the inspection findings came on the same day that more people arrived in Dover aboard small boats.

A young girl wrapped up in a jacket and gloves and wearing a face mask held a woman’s hand as she walked along the quayside at the Kent port.

Others wore lifejackets and woolly hats as they sat waiting to be helped by officials.

One man seen at the port had a bandaged hand.

Temperatures in Dover overnight dipped below zero but low winds have seen a number of small boats risk the dangerous journey from France, it is believed.

Several Border Force boats have been active in the Channel on Monday for hours, on what may be one of the busiest days of the year for crossings.

At least 115 people crossed the English Channel to the UK aboard small boats on Monday, the Home Office has confirmed.

Seven boats were dealt with by Border Force on what has been the busiest day for crossings in 2021 so far, according to data from the PA news agency.

It surpasses the figure for January 9, when 103 people crossed the Dover Strait.

The latest journeys come less than a week after a boat is believed to have capsized off the coast of France, possibly leading to the deaths of one of those on board.

Three people suffering from hypothermia were taken to hospital after the failed crossing but French authorities said there may have been a fourth person on board.

Following more crossings on Sunday, more than 650 people had crossed the English Channel aboard small boats so far in 2021, more than double the figure for the same time last year, according to data analysis by the PA news agency.