The Tamils, whose boat was intercepted by a customs vessel last week, will be transferred to the custody of a Sri Lankan naval ship at sea in coming days.

They will be returned to Sri Lanka, the country they originally fled, raising concerns Australia will breach its non-refoulement obligations under international law by sending people back to a place where they face threat of persecution.

At the most recent assessment of Sri Lanka at the United Nation’s Universal Periodic Review – during which all UN countries have their human rights records assessed by fellow member states – Australia accused the Sri Lankan government of complicity in human rights abuses.

Australia recommended Sri Lanka should: “Take action to reduce and eliminate all cases of abductions and disappearances; take action to reduce and eliminate all cases of abuse, torture or mistreatment by police and security forces; and take action to facilitate greater participation by citizens and civil society in helping to implement human rights action plans.”

Other countries such as Britain, New Zealand and Canada also said they had “serious concerns with respect to Sri Lanka’s human rights situation”.

Australia made the comments in November 2012, in the current cycle of the UPR that runs until 2016. The statement is Australia’s most recent position to the review on Sri Lanka, and the Department of Foreign Affairs and Trade did not resile from the stance on Sunday.

A spokesperson said: “The Australian government considers engagement with Sri Lanka to be the most effective way to encourage progress on human rights issues. Genuine advances in accountability and reconciliation will only be possible with the co-operation of the Sri Lankan government.”

The Australian government said it would work closely with the Sri Lankan government, opposition parties and other groups to promote reconciliation in the country.

But it remained silent yesterday on its plans to transfer the asylum seekers into the custody of Sri Lankan authorities.

Fairfax and other media organisations, as well as human rights organisations such as Human Rights Watch and the Human Rights Law Centre, have documented cases of asylum seekers who have been tortured upon return to Sri Lanka.

The Asian Human Rights Commission has detailed 400 cases of torture including “beatings, sometimes with the victim hung upside down, to the use of chilli powder applied to the eyes and genitals".

Colombo and former war-zone cities such as Jaffna, Kilinochchi and Mullaitivu, are notorious for "white van disappearances", where vans without number plates snatch people from the street.

The most recent UN report lists 5676 “outstanding cases” of enforced or involuntary disappearances in Sri Lanka.

And members of Sri Lanka’s navy – into whose custody the asylum seekers are expected to be transferred – are allegedly among the most prolific people-smugglers in the country.

Four navy officers and sailors have been arrested and charged with people-smuggling. The alleged leader of the biggest smuggling racket, Lieutenant Commander Sanjeewa Annatugoda, briefed Australian border protection officials on navy counter-smuggling measures.

The Sri Lankan government has consistently denied abuses by its security forces, and President Mahinda Rajapaksa says his administration brought peace after 30 years of brutal civil war.

The Liberation Tigers of Tamil Eelam – a terrorist organisation proscribed by Australia – was routed by the Sri Lankan army in 2009 .

Immigration Minister Scott Morrison is to visit Sri Lanka on Wednesday. He will attend a commissioning ceremony for two patrol boats Australia has given the Sri Lankan navy to assist with asylum seeker interdiction.

A motion will be put before the Senate on Monday by Greens senator Sarah Hanson-Young that condemns the government for its secrecy over the asylum seekers and calls on it to explain the transfer on the high seas.