A human rights and refugee lawyer in Sri Lanka has accused Australia of breaching international obligations over the recent return of a group of asylum seekers who reached the Cocos Islands.

Key points: Lawyer says Australian Government "talking rubbish" about breaking people smugglers' business model

Lawyer says Australian Government "talking rubbish" about breaking people smugglers' business model Says most Sri Lankan asylum seekers buy their own boats

Says most Sri Lankan asylum seekers buy their own boats Accuses Australia of breaching Refugee Convention

Lakshan Dias is representing some of the 12 men, women and children who reached the Cocos-Keeling Islands in early May and were subsequently flown back to the Sri Lankan capital, Colombo.

Two from the group are in a remand prison awaiting court proceedings and could face severe penalties for leaving Sri Lanka by boat.

Mr Dias told PM that Australian politicians were foolish to say they had broken the people smugglers' business model, saying they misunderstood how people made the journey from Sri Lanka.

"Australia's Government is talking rubbish. They have no clue of how and what and the type of boat journeys," Mr Dias said.

"[In] most of the cases, people collectively go on these boat journeys.

"In Sri Lanka, there are not organised people smugglers. It is totally different from what is happening in Indonesia and Malaysia."

Mr Dias said it was more common for Sri Lankan asylum seekers to go it alone.

"These kind of people get a boat from a boat owner and they collectively get money for food and fuel and everything and go on a boat journey to Australia," he said.

"That cannot be looked at as a people smuggling business."

Return to Sri Lanka a 'violation of Refugee Convention'

Mr Dias said his clients claimed they were not given adequate time to explain their situation.

"They were given only 20 minutes to talk to an immigration officer, with a Sinhalese interpretation and there was no time to tell their story, tell their grievances, tell their well-founded fear," he said.

"They were just asked two things including name and address and so on and not allowed to talk."

Mr Dias said the treatment of his clients represented a breach of Australia's international obligations to the UN Refugee Convention.

"Throughout the whole episode, they have requested the assistance of lawyers which was not given," he said.

"And they said they cannot go back, they have a well-founded fear and nothing was seriously considered.

"I feel this is a violation of the [UN] Refugee Convention 1951 and all human rights norms by Australia."

There is little scope for legal recourse for his clients, but Mr Dias intends to challenge the decision to return the asylum seekers to Sri Lanka.

He said he would "exhaust all available legal remedies in Australia".

Border Force essential for economic security, PM says

On the campaign trail today, the Prime Minister was in Darwin to praise the work of Australian border security officers, which he said were essential for economic security.

"Underpinning the economic security of our nation is a strong force on the border, the Australian Border Force," Mr Turnbull said.

But Mr Turnbull was keen to point out a perceived disparity between Coalition and Labor policy on immigration.

"We have now more than two dozen — 25 at latest count — of [Labor's] candidates and backbenchers who are unhappy, disassociate themselves with, qualify their support for our policy and the reality is that they are just the tip of the iceberg," he said.

Labor Leader Bill Shorten refuted that claim.

"He has clearly decided that he is going to say as often as he can that Labor won't tackle the people smugglers," he said.