Asylum seekers branded security threats by the Australian Security Intelligence Organisation have been involved in a spate of suicide attempts inside the nation's detention network.

Two Tamils given adverse assessments by ASIO have attempted to kill themselves at a detention centre in Melbourne's north in the past month - one of them twice.

A third man stood screaming with an electrical cord clutched in one hand late on Sunday at the same spot where a friend had swung by the neck until he almost died three nights earlier.

The man, one of 78 rescued by the Australian customs vessel Oceanic Viking in 2009, had become distraught listening to a Mother's Day special on radio, and remembering how his mother was killed in Sri Lanka's civil war when he was 13.

A total of 47 people in Australia have been given adverse security assessments, leaving them with no prospect of release into the community or resettlement in another country. Eight of them - six Tamils, an Iranian and a Rohingya Burmese - are being held at the Melbourne Immigration Transit Accommodation complex in Broadmeadows.

They are caught in a legal limbo, not permitted to see the evidence against them, nor to know the criteria ASIO uses to make its assessment.

Although they make up less than 1 per cent of all people to have arrived by boat and sought refuge in Australia since 2010, a surge in arrivals over recent weeks - including 670 this month - could mean more adverse findings.

After a recent determination by ASIO, a Tamil woman, Ranjini, and her two children were taken into custody at Sydney's Villawood detention centre last week. It is believed ASIO found her former husband was a driver for Tamil Tiger separatists.

Melbourne refugee advocate Julian Burnside said there was no effective review of ASIO assessments. ''The fact that a person has been adversely assessed by ASIO does not mean they are a terrorist. They may have had a cousin who was involved in people smuggling or some other relatively minor thing,'' Mr Burnside said.

''They face the possibility of being in detention forever ... What the government says is: 'We will try and find another country'. They say to other countries: 'Will you take this refugee from us, with an adverse security assessment?' As you can imagine, that's a hard sell.''

The ALP national conference last year passed a resolution calling for an independent review of ASIO assessments but the government has yet to act.

The Age has been passed a letter by a group of nine men with adverse assessments sent to Immigration Minister Chris Bowen last August. ''We are grateful to Australia, particularly to the [Immigration] Department, as we have been accepted as refugees, due to the threat we face in our native country,'' the letter reads.

''But, we are not allowed to enter Australia, because ASIO perceives that we pose a security risk to Australia. ASIO refuses to tell us why they perceive so. We tried a number of times to explain to ASIO and the department that we would never imagine causing any harm to Australians or Australia, which opened the doors for us.''

An employee at the Broadmeadows centre, who asked not to be identified, described the situation as "Kafka-esque" and said many detainees were victims of trauma and torture.

Even those who could sleep were often woken at night by their neighbours screaming, with up to 70 per cent of detainees supplied with anti-depressants, anti-anxiety medication or sleeping pills.

The Immigration Department said a GP visited the centre three times a week, in addition to a nurse clinic and a psychologist being on site five days a week, and a consultant psychiatrist also calling each fortnight. A spokesman said no incident was reported there on Sunday.

But The Age has been told Jasee was restrained by friends after his threat to harm himself.

Aran Mylvaganam, a Tamil community activist, said Jasee was crying when he spoke to him about 1am on Monday.

''It was Mother's Day. It reminded him of all the negative things that have happened in his life,'' Mr Mylvaganam said.

Refugee lawyer David Manne said the system amounted to a denial of natural justice.

The Age sought an interview with Immigration Minister Chris Bowen to discuss the government's plans for asylum seekers given adverse assessments, but was referred to Attorney-General Nicola Roxon, who did not respond.

Refugees' ASIO Despair