Prime Minister Tony Abbott has described Sri Lanka as a ''society at peace'', amid mounting speculation that two boats carrying Tamil asylum seekers have been handed over to the Sri Lankan navy in the middle of the ocean.

Speaking to 3AW on Thursday morning, Mr Abbott said it was no secret that Australia was turning back boats on the high seas.

''We said before the election that one of the policy options that we reserve the right to use, were it safe to do so, is turning boats around,'' he said.

On Wednesday, Fairfax Media revealed that 50 Sri Lankan asylum on board one boat were asked four basic questions by immigration officials via a teleconference, as part of a screening process. It is understood the asylum seekers are likely to be handed over to the Sri Lankan navy.

The questions asked included the passengers' name, country of origin, where they had come from and why they had left.

Another asylum seeker boat, which held 153 passengers who were also Sri Lankan Tamils, has since been transferred to a navy boat, after civilians lost contact with the boat on Saturday morning.

When asked whether the government was sending asylum seekers back to the country they fled from, Mr Abbott replied: ''There does need to be a process because we do have international obligations so there does need to be a process.

''But I want to make this observation, Sri Lanka is not everyone's idea of the ideal society but it is at peace . . . a horrific civil war has ended. I believe that there has been a lot of progress when it comes to human rights and the rule of law in Sri Lanka.''

Immigration Minister Scott Morrison has refused to comment on the two boats – one carrying 153 asylum seekers and the other carrying 50 asylum seekers – maintaining that the government does not comment on ''speculation or reporting'' regarding on water operations.

Labor's immigration spokesman Richard Marles, who has so far kept a low profile on the issue, said it would be a disgrace if asylum seekers were handed over to Sri Lanka, and demanded the government come clean with the Australian people.

''They have a right to know and this minister is treating everyone with contempt in denying us the right to know,'' he told Sky News on Thursday.

Asked later on Thursday if Australians had a right to know what was happening with asylum seekers on the two boats, Mr Abbott said: ''The public deserve safe and secure borders.''

''They deserve a country that has not become open for the wrong kind of business, the people smuggling business," he told reporters in Melbourne.

"Everything we do is consistent with safety at sea and everything we do is consistent with our international obligations.

"It is a peaceful country. It is a peaceful country. I don't say it's a perfect country, not even Australia is that. But it is a peaceful country and all of us should be grateful that the horrific civil war is well and truly over and that is to the benefit of every single Sri Lankan, Tamil, Sinhalese. Everyone in Sri Lanka is infinitely better off as a result of the cessation of the war."

Despite Mr Abbott maintaining that Sri Lanka is now a society of peace, advice from the Department of Foreign Affairs and Trade says Australians should exercise a ''high degree of caution'' due to the ''unpredictable security environment'' in the country.

''You should avoid all demonstrations and large public gatherings as they may turn violent or be a target for politically-motivated attacks. Police have used tear gas in response to protests,'' the advice on the department's website says.

''In the Northern Province of Sri Lanka, which includes Mannar, Vavuniya, Mullaitivu, Kilinochichi and Jaffna Districts, post-conflict security force activity is ongoing.''

Greens leader Christine Milne said if the transfers with the Sri Lankan navy go ahead, it would the first example of the Abbott government sending people directly back to where they have been persecuted.

''The Prime Minister must explain to Australians how he can claim that what he is doing is not a human rights abuse,'' she said. ''How can he claim what he is doing is not a contravention of the convention when he is engaged in total secrecy?

''It is absolutely wrong for Australia to return people seeking asylum to the countries in which they were being persecuted. It is wrong. It is shameful.''

According to a member of the co-ordinating committee of the Gummudipoondi camp for Tamil refugees, who were on board the boat carrying 153 asylum seekers, in the Indian state of Tamil Nadu, members of the Tamil Nadu police force's "Q" branch, which monitors the activities over refugee camps, had swept his camp and several others seeking information.

"They have been here asking, investigating, looking for the information," said the coordinating committee member who gave his name as William.

William said there were 17 people missing from his camp who are assumed to be aboard the vessel and that he had been in contact with the families over the past few days.

"They are extremely worried, crying, desperate for information about what has happened, pleading for some country to accept them so they do not be made to return to Sri Lanka," he said.

"They believe that if the refugees are made to return to Sri Lanka they will face severe harassment, possibly even torture, from the local authorities in Sri Lanka. Of course there is a lot of concern."

with Jason Koutsoukis

Follow us on Twitter