The Australian federal police declined the opportunity to interview a Sri Lankan asylum seeker sent back from Christmas Island who alleged he had been “severely tortured” by local police on his return, a cable obtained under freedom of information laws has revealed.

The cable, sent to Canberra from the Australian high commission in Colombo in August 2010, states that the AFP did not interview the alleged torture victim so as to avoid interference with an investigation being conducted by the Sri Lankan police.

“In the interests of keeping our distance from the Sri Lankan investigation, we do not intend to take up the offer to meet with him,” the cable states.

It states the man was arrested as a result of a “disruption” – or operation to combat suspected people smuggling – that had occurred a week previously. “The detained suspect is a Sinhalese returnee from Christmas Island,” it reads.

The cable reveals that an AFP officer instead “managed to sight” the man while he was in Sri Lankan custody and deduced that he “appears in good health” but it is unclear how much time had elapsed between the alleged torture and the AFP viewing the returned asylum seeker. The case was eventually written off as “unsubstantiated”.

The cable also makes reference to a letter from the returned asylum seeker’s lawyer, which lays out the torture allegations in detail. It makes clear that the high commission was in possession of this letter at the time the torture allegations were made.

The legal letter, which formed part of the returned documents from a Freedom of Information Act request initiated by Guardian Australia and the Human Rights Law Centre, sheds further light on the allegations.

It states that the alleged torture victim had received a call from the Australian high commission in Colombo seeking to return some of his possessions from Christmas Island, a year after his return. It says just a few days after this call, the man was contacted by the Criminal Investigation Department (CID) of the Sri Lankan police.

According to the letter, the man was later arrested and witnesses reported he was “publicly tortured by CID in front of other villagers, mother and wife”. The letter states that the man was tortured again in custody and that his lawyer had been prevented from visiting him.

“Usually Sri Lankan police do not allow victims to say that they were tortured. They somehow prevent this kind of things by threatens [sic]. We need doctors to inspect … immediately,” the letter states.

The cable from the high commission says the alleged torture victim would be seen by a doctor and that the CID officer in charge of the case had told the AFP the torture allegations “had no basis”. The cable also states that the initial arrest was conducted by the Sri Lankan navy.

According to Amnesty international, torture in police custody is “rampant” in Sri Lanka, with the country’s national human rights commission recording 86 torture complaints in the first three months of 2013 alone.

The case referred to in the cable is one of four brought to the Australian high commission in Colombo as of June 2013.

In April 2013, the foreign minister at the time, Bob Carr referenced these four cases and said there was “absolutely no evidence of an abuse of human rights” on two of them – including the August 2010 case – following investigations by the high commission.

Guardian Australia contacted Carr, who said he stood by these remarks and added he would not comment on the case where the AFP had declined to interview an alleged torture victim.

Emily Howie, director of advocacy and research at the Human Rights Law Centre, said the August 2010 case showed that Australia was not fulfilling its non-refoulement obligations under the refugee convention.

“If this is how Australia investigates complaints of severe torture how can we accept government claims that Sri Lankan returnees are not at risk of harm?” she said.

“This kind of monitoring of returnees is woefully inadequate considering the gravity of the complaints made. It is difficult to accept government assertions that Sri Lankans are not harmed on return if an Australian official fails to take the most basic step to look into allegations of extremely serious abuse.”

Sri Lankan asylum seekers who arrive in Australia by boat are subject to the “enhanced screening” process – a fast-track claim process, which has been condemned by the UN as unfair and unreliable.

More than 1,000 Sri Lankan asylum seekers have been returned from Australia.

Greens senator Lee Rhiannon said the case was an example of Australian officials ignoring evidence of human rights abuses in Sri Lanka.

“Time again we have seen that Australian officials are prepared to disregard evidence of torture by Sri Lankan officials that have been exposed by human rights organisations and the media, because it suits their domestic policy,” she said.

“This is a tragic response to very serious and continuing human rights abuses in Sri Lanka that are a result of Australia’s domestic immigration policy.”

A spokesman for the AFP confirmed that they had “engaged local authorities” with regards to the torture allegations. But added that despite being invited to interview the alleged victim and viewing him, “Australian Government agencies, including the AFP, do not have the local authority to conduct any investigations in Sri Lanka.” - The Guardian