The Bibby Stockholm, moored at Portland in Dorset, has been used since last August as ministers sought to find alternatives to hotel accommodation for those waiting for decisions on their asylum applications.

But the vessel has been plagued with issues - including an outbreak of Legionella bacteria onboard - and in December, police confirmed one of the people onboard had died, with reports suggesting the man had taken his own life.

The Home Affairs Committee, made up of cross-party MPs, visited the barge and have now written to illegal migration minister Michael Tomlinson to raise serious concerns about the conditions being faced by those living on the vessel.

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Chair of the committee, Dame Diana Johnson said MPs had been "disheartened to see some of the living conditions on the Bibby Stockholm", saying they found "many individuals having to share small, cramped cabins (originally designed for one person), often with people (up to six) they do not know (some of whom spoke a different language to them)".

She added: "These crowded conditions were clearly contributing to a decline in mental health for some of the residents, and they could amount to violations of the human rights of asylum seekers."

The Labour MP also said it was "concerning" that in their short visit "many asylum seekers expressed mental health concerns", saying: "It was alarming that one asylum seeker told a member of the delegation that they had had thoughts of suicide as a result of having to reside on the barge.

"Although we were assured that the relevant safeguarding team would work with this particular individual, we are extremely concerned about the apparent lack of mental health support for those on the barge."

The committee chair also highlighted "very limited access" for Muslims to religious services, and "discrepancies" between the accounts of officials and asylum seekers, including "inconsistent" information about access to GPs.

In a statement released after the letter was published, Dame Diana said: "We are concerned that housing asylum claimants on Bibby Stockholm is leaving them in a claustrophobic environment, isolated from external support including legal advice, and without important links to community, faith or family potentially for months on end.

"The government must not forget that those seeking asylum could have experienced severe trauma. They are vulnerable young men who will be in need of critical help."

The committee called for "all suitable steps to ensure mental health support is available" onboard, especially in light of the "tragic" death at the end of last year.

Earlier this week, Home Secretary James Cleverly appeared in front of the committee and said he was "totally confident" the Bibby Stockholm was meeting all legal requirements.

He added: "We take both the physical and the mental health of the people who are in the asylum estate very seriously."

A Home Office spokesperson said: "The health and welfare of asylum seekers on board the Bibby Stockholm is of the utmost priority, and we constantly work to ensure the needs and vulnerabilities of those residing on the vessel are identified and met.

"Asylum seekers are screened to identify vulnerable individuals and ensure they are placed in suitable accommodation.

"There are rigorous safeguarding processes in place on the barge. Residents have access to health and social care services, including mental health support.

"If concerns are raised about any aspect of the service delivered, we work with the provider to ensure these are swiftly addressed, and Migrant Help 24/7 is also available every day of the year."

Airbase row

Meanwhile, a local council has launched a fresh legal challenge against the government over its plan to house asylum seekers at a former RAF base in Lincolnshire.

The Home Office is seeking planning permission to use RAF Scampton to accommodate 2,000 male asylum seekers - again as an alternative to using hotel rooms.

But West Lindsey District Council has voted unanimously against the application, claiming the government's plan to use legislation to secure the site lacked transparency and limited any public consultation.

Council leader Trevor Young also said the base - previously home to the Red Arrows and the Dambusters - was "a place with significant history" and it was "important for us to preserve the historical and architectural integrity".

A Home Office spokesperson insisted RAF Scampton would be protected and the council receive £3,500 for every person housed on the site.

The council is currently appealing a ruling by the High Court that use of the site to accommodate asylum seekers was lawful.