The first 50 asylum-seekers in the UK have now received notice from the Home Office that they face deportation to Rwanda, where they risk being permanently resettled even if officially confirmed as refugees.

With a taste for irony reminiscent of a certain Russian leader, British ministers defend this plan for the mass transit of “tens of thousands” of human beings against their will as a “solution” to the problem of human trafficking.

In reality, the Rwanda deal – which promises the East African country an initial £120m to host those who have made ‘illegal’ entry into the UK – borrows from the same semi-colonial playbook as Australia’s recent failed experiment in offshore ‘processing’.

From 2012 onwards, asylum-seekers arriving by boat to Australia were forcibly sent to the small pacific island nation of Nauru and to Papua New Guinea’s Manus Island, where they were detained indefinitely in squalid and repressive conditions.

As with the Rwanda deal, Australia outsourced responsibility for those seeking sanctuary to poor and over-burdened countries with questionable human rights records. The Australian system also offers a disturbing insight into the kind of treatment asylum seekers can expect.

I have spoken at length to current and former detainees about their experiences in Australia’s offshore system. Their shocking accounts – all shared under pseudonyms – should provide an urgent wake-up call to British citizens, and their government, to pull the plug on this scheme or face being complicit in a humanitarian disaster.

Many of the men I interviewed had spent almost a decade of their lives in custody, suspended in an anxiety-inducing state of legal limbo.

Mohammed, a refugee from Iran, was sent to Nauru at the age of 15 and was not released until recently, aged 25. He described offshore detention as a chaotic, “barbaric system” that strips people of their humanity.

Arguably, the use of detention for immigration ‘offences’ is always morally wrong. But offshore detention gives licence to special forms of abuse, existing as it does in a ‘state of exception’ beyond proper legal checks and scrutiny.

Those I spoke to describe the system as a violent Kafkaesque nightmare; deprived of information about their case, cut off from regular communication with the outside world, and many miles from potential support networks, they suffered in fear and isolation.

Many saw this as part of a deliberate strategy of ‘psychological warfare’, designed to break their spirits. For Aadav, a refugee fleeing violence in Sri Lanka, indefinite detention on Manus Island “felt like a cut to the neck without bleeding”. In the words of Kasun, another Sri Lankan, the very construction of detention camps was made “to suffocate people”. Detainees were demonised as criminals and terrorists and referred to as numbers by staff, rather than by their real names.

Food and hygiene in the camps were poor, and medical support close to non-existent. Several detainees have died of medical negligence. Those who were permitted to go to the hospital for much-needed treatment could expect to be shackled in handcuffs and escorted by guards. In his celebrated account of life on Manus Island, Kurdish-Iranian author Behrouz Boochani describes detention as a ‘Kyriarchy’; a system of oppressive power that degrades refugees to the point where they lose touch with their own humanity and that of others.

It is no surprise that all those I spoke with reported high rates of anxiety, depression and PTSD in offshore detention. There were frequent cases of self-harm and suicide, of which I heard horrific stories. Indeed, one academic study found that rates of self-harm among those in offshore detention in Nauru were up to 216 times higher than that of the general population in Australia.

There were also mass hunger strikes, with several hundred people taking part in one such protest on Manus Island in 2015. The action, which was led by Yusef and others, was part resistance, part cry of despair. Yusef told me he did not starve himself “to get any answer. I went on hunger strike to just die. I was powerless, I was helpless and hopeless”.

Those who challenged their oppression could expect severe reprisals. Yusef and several other protest leaders were removed from the detention centre and placed without charge in a grim Papua New Guinea jail. Even those who put their complaints in writing risked punishment.

Here, there are already disturbing echoes of what we know about Rwanda’s treatment of refugees. Lewis Mudge, the central Africa director at Human Rights Watch, told The Guardian that Congolese refugees had been left to “rot in jail [in Rwanda] for protesting their living conditions”.

Violence from guards was also common. One detainee describes having his throat cut while on Manus Island. Another man was reportedly killed by guards and workers in the riots, which saw more than 70 asylum-seekers and refugees injured.

In another indication of what may await those sent to Rwanda, refugees describe frequent cultural misunderstandings and conflict with island locals, whose customs, dress and behaviour were alien to them.

The men I spoke to were very clear about the political purpose this cruelty served. They saw their suffering as a deliberate strategy – a cross-border spectacle of suffering engineered by populist politicians to deter others from seeking sanctuary in Australia and encourage self-deportation.

As Mohammed noted, “the system is designed to destroy people… to force them to go back to where they belong”. This was echoed by Ali, an Afghanistan national who worked for Western contractors during the war, and now fears reprisals by the Taliban. He feels detainees have been used “as a shield to stop others” from attempting to travel to Australia.

Australia began winding down its failed experiment in offshore processing several years ago, after widespread protests and successful legal challenges. An estimated £5bn was wasted on a cruel and chaotic system, which achieved little beyond the enrichment of private contractors.

Today, more than 100 people are still awaiting resettlement from Papua New Guinea, including Ali. Even for those who have escaped the Pacific island nightmare, the scars still endure, as does the lasting stain on the country’s reputation.

The UK government maintains conditions in Rwanda will be humane. Home secretary Priti Patel has said the UK government’s offshore detention plans are “not comparable” with the Australian system – but this lacks credibility given leaked documents identifying Australia’s approach as a key inspiration. Such reassurances are also difficult to square with the UK’s apparent goal of deterrence.

I asked Ali what his main message was to the UK as it embarks on the same fateful course. He said: “A person will not leave his home country or his home without his life being in danger… He needs a safe place and he came to your house, if you give him protection… he will help your country’.

Ali predicted that there will be ten years of failure in Rwanda, after which the “UK people will also say that you were wrong to do this”. We cannot say we were not warned.