Scott Morrison has questioned a psychiatrist's claim that the Immigration Department tried to cover up figures showing the extent of mental health concerns among child detainees at Christmas Island.

Speaking to the ABC's Insiders program, the Immigration Minister also rejected accusations the Government stopped lawyers from advising a group of Tamil asylum seekers that have been sent to Nauru.

Earlier this week psychiatrist Dr Peter Young, who was the director of mental health services on Christmas Island for three years until earlier this month, gave explosive evidence at a human rights inquiry into detention centres.

He told the inquiry Immigration Department officials reacted with alarm at figures showing the extent of mental health concerns among young detainees and "asked us to withdraw these figures from our reporting".

Mr Morrison told Insiders people should not jump to conclusions about the claim.

"I've spoken to the secretary about that and he's written back to the commissioner and outlined what is actually occurring," he said.

"I mean, in these meetings there is always two sets of versions of what has occurred.

"What they're working through is a process to get the best possible reporting of mental health in these facilities.

"The chief medical officer and the independent health adviser to the secretary are working with OHMS and are bringing in other experts to ensure we get the best measure of reporting on mental health."

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 17 minutes 12 seconds 17 m Scott Morrison joins Insiders

Insiders host Fran Kelly asked: "What does that mean? That Peter Young wasn't told to take those statistic out?"

"What I'm saying is there is a process that is underway. That process is not completed," Mr Morrison replied.

"There was testimony that was given but I think it's important with this inquiry that we don't leap ahead and make a whole bunch of conclusions until that inquiry has been able to go through all its evidence and that evidence can be properly tested and the Department has the opportunity to respond to what has been put at that inquiry.

"That's what the secretary has done and I am waiting for the outcome of that process."

Morrison rejects claims Tamils were denied access to lawyers

Mr Morrison was also questioned about whether 157 asylum seekers had access to lawyers before they were sent to Nauru.

The group of men, women and children left India by boat and was intercepted and held at sea for almost a month before being sent to the Cocos Islands and then to Curtin Detention Centre in Western Australia.

The group was then sent to Nauru after they all declined to talk to Indian officials about returning to the port they departed from.

Lawyer George Newhouse, who represents the 157 Tamils, on Saturday accused the Government of "trafficking" the group, and said they were not given the chance to talk to their lawyers about their options before they were moved to Nauru.

But Mr Morrison has told the ABC's Insiders program they had access to lawyers before they rejected the chance to talk to the Indian officials.

"It's not true to say that there was no access to lawyers," Mr Morrison said.

"On the 29th of July, the leaders of that group, who were the appointed plaintiffs in the case, had access to their lawyers and there was a discussion. Following those discussions, 157 people coincidentally decided not to take up that offer."

He said he is confident more than two-thirds of the group were long-term residents of India.

"They had been residents in refugee camps, those camps set up in Tamil Nadu and in other villages across Tamil Nadu," he said.

"They had been in schools and living with family. We had teenagers on that ship who were born in India."

Opposition Leader Bill Shorten says there has been too much secrecy around the group's treatment.

"If the news is good [the Government] will be out there with rent-a-quote on the front doorstep boasting about how well they have done," he said.

"Every time it gets a bit hard this Government goes missing. I think the Government needs to come clean on everything that's happened with this matter, everything that's transpired with their negotiations with the Indian government."

50 children sent to Nauru 'because offshore processing is universal'

There are 50 children in the group, and Mr Morrison was questioned on why they were sent to Nauru, rather than being placed in community detention, in the same week doctors have aired fresh concerns about the impact detention has on child mental health.

"Offshore processing is a universal policy and when you create exceptions to that then you create an incentive for children to get on boats," he said.

"I hope the days now are long gone where children are dying at sea and my officials and officers who work for Customs, and the Navy officers have to scoop children out of the water.

"We have put considerable resources into Nauru to ensure it's fit for families.

"The accommodation is air conditioned for children, there's play equipment, there's shaded areas for learning, there are covered areas, air conditioned for the schooling."

Doctors who have been working on Christmas Island told a human rights inquiry this week the paediatric care in the centre is basically non-existent.

Dr Young told the inquiry there have been 128 cases of child detainees committing acts of self-harm in the past 15 reporting months.

He said he was aware children had tried to poison themselves or ingest harmful substances, and said banging heads against walls is common.

Mr Morrison said he was "very troubled" by the claims but added: "Equally I'm already acting along the lines I've already mentioned in terms of the support and facilities we're putting in and also by ensuring we're not getting children going into these facilities and we're stopping them getting on boats in the first place and I'm getting them out."

"These inquiries are raising a whole range of questions and there's a whole bunch of testimony that is being provided.

"Now, that has to be tested against the broader context of what's occurring and what I want to know is what the facts are and when I have the full facts then I can take further action to the action I've already taken."

Greens immigration spokeswoman Sarah Hanson-Young says there is widespread public support to move all children out of detention immediately.

"Australians across the country are increasingly uneasy and nervous about the welfare of these children, young people harming themselves, children who don't even introduce themselves by their own names any more, only by the ID numbers they've been given," she said.