Australia’s sudden decision to withdraw financial support and housing from a group of asylum seekers and refugees in Australia has drawn international criticism and formal complaints to three senior rapporteurs at the United Nations.

It has also inspired a public pledge by the Victorian government to house, feed and financially support any refugees and asylum seekers left homeless or destitute by the commonwealth’s decision.

Last month, the immigration minister, Peter Dutton, announced the imposition of a new “final departure bridging visa” for refugees and asylum seekers brought to Australia from Nauru or Manus for medical treatment.

So far, 63 asylum seekers and refugees across Australia have been issued with the new visa – they have had all government financial support ended and face eviction from government-supplied housing in one week.

But it is understood up to 400 people – including families with infant children born in Australia – face having government support withdrawn in an effort to encourage them to abandon their protection claims, or return to Australia’s offshore detention islands of Manus and Nauru.

In response, the Human Rights Law Centre in Australia and the Geneva-based Global Initiative for Economic, Social and Cultural Rights are set to send urgent submissions to three United Nations special rapporteurs: on the right to adequate housing; on extreme poverty and human rights; on torture and other inhuman or degrading treatment or punishment.

The UN’s special rapporteurs hold mandates from the United Nations Human Rights Council, the powerful UN body to which Australia is seeking election in November.

The joint submissions call on the rapporteurs to urge the Australian government to abandon the final departure bridging visas, reinstate housing and income support, and allow those seeking asylum to apply for refugee status in Australia. It also asks the rapporteurs to publicly condemn the government’s actions.

“The purpose and effect of these government actions is to cut off vulnerable people from basic supports as a means of pressuring them to return to a place where they fear serious physical and/or psychological harm,” they say.

“The government actions risk rendering affected people homeless and destitute as they will have no income support and little chance of finding work to provide for their food, housing, clothing and other basic needs.”

The submissions argue the government’s imposition of the final departure visa is a breach of its international obligations under several international treaties, including the convention against torture and other cruel, inhuman or degrading treatment or punishment.

Lucy McKernan, Geneva representative for the Global Initiative for Economic, Social and Cultural Rights, told the Guardian rendering people deliberately destitute was a flagrant breach of human rights.

“Subjecting vulnerable people to deliberate destitution is morally and legally indefensible. It is also embarrassing to Australia as it trumpets its credentials as a candidate for the UN Human Rights Council.”

Subjecting vulnerable people to deliberate destitution is morally and legally indefensible. Lucy McKernan

McKernan said forcing people into poverty was “deeply harmful” to them.

“It also deeply harms Australia’s claim to be a principled protector of human rights.”

Daniel Webb from the Human Rights Law Centre said the new visa regimen forced refugees and asylum seekers to face an invidious choice.

“Dutton is forcing people to choose between destitution here or danger and abuse elsewhere,” he said. “Essentially, they are being starved out.

“It’s awful. People are panicking every time the phone rings. They’re terrified of being kicked out on to the streets. These men and women were just starting to rebuild their lives in our communities. Now suddenly they’ve been completely cut off and are a week away from potential homelessness.”

The submissions follow an announcement by the Victorian premier, Daniel Andrews, that the state government would provide $600,000 for a housing fund to cover accommodation costs, as well as financial assistance to cover food, clothes, public transport and medicine.

“Malcolm Turnbull might be prepared to stand by and let these families starve while they wait to leave Australia but we won’t,” Andrews said. “We’re making sure these families will have a roof over their head, clothes on their back and food on the table.”

The description of a bridging visa as a “final departure bridging visa” has not previously been a part of the Australian asylum system.

Dutton said that the government brought the changes to stop asylum seekers and refugees brought to Australia from Australian-run offshore immigration centres for medical treatment from exploiting the asylum system.

“The con is up,” he said. “They were brought to Australia on the premise that once their medical needs were met they would return to Nauru or Manus.

“The medical care has been provided and through tricky legal moves they are now prevented from being returned to their country of origin, Manus, or Nauru. In some cases, this con has been going on for years, costing the Australian taxpayer tens of thousands of dollars for each individual.”

It costs $573,000 a year to house a single asylum seeker or refugee in offshore detention, according to the government’s own audit. The auditor says it costs about $40,000 to have someone supported in Australia.

Dutton accused lawyers who assisted asylum seekers and refugees exercising their legal rights before the courts of being “un-Australian”.

The Guardian understands 63 people across Australia have been issued with the new final departure bridging visa, most in Victoria (26), and New South Wales (19).

Under the new visa, valid for six months, asylum seekers and refugees immediately lose all government payments – currently $200 a fortnight – and are given three weeks to leave government-supplied housing.

Refugees and asylum seekers will have access to Medicare and children will be able to attend school. Refugees and asylum seekers will be allowed to work, although the practicality of finding employment while on a six-month visa and facing an uncertain future is limited.

While only 63 people have been issued the new visa, it is understood up to 400 people – known as the Let Them Stay cohort – face its imposition in coming months. They are refugees and asylum seekers who have been brought to Australia from Manus and Nauru for medical treatment, including complex surgery and long-term mental health treatment, or to give birth. Some have been victims of rape and assault on offshore islands.

The group includes 37 children who have been born in Australia, and more than 100 children in total – many of whom attend Australian schools.

A significant proportion have court injunctions preventing their forcible return to offshore islands without warning.

The excoriating submissions to the UN special rapporteurs are especially awkward for Australia at present.

Australia appears certain to win election to the UN’s Human Rights Council in November. It was competing against Spain and France for one of two spots on the council before France withdrew, all but assuring Australia’s ascension for a three-year term.