A TINY Australian-born baby was among 14 asylum seekers herded onto a plane from Adelaide to Christmas Island on Thursday.

The four families were the latest to be removed from the Adelaide Hills Inverbrackie detention centre.

More than 70 babies have been born in Australia to asylum seeker mothers, and once they are “old enough” – in this case, eight weeks or younger – they and their families are sent back to Christmas Island.

Sources said the youngest baby in the group was about six weeks old, but a spokesman for Immigration Minister Scott Morrison said all the children were aged from eight weeks to six years and that it was a “normal transfer process”.

“The Minister is advised the families have no further medical treatment required and have been deemed fit to return to Christmas Island,” he said, adding that the detainees were notified in advance.

Lawyers Maurice Blackburn are acting for the 71 babies.

Principal Jacob Varghese said that was a “growing number” as they continued to field new inquiries.

Pregnant asylum seeker women are still arriving in Australia to give birth before being sent back.

“(Christmas Island) is not an appropriate place to be holding children,” Mr Varghese said.

“The more children the Government moves there, the more concerned we are.”

Greens immigration spokeswoman Sarah Hanson-Young also said the island was no place for children.

She said she had been told that everything on Christmas Island was being severely rationed, and the shop where families lined up for provisions had run out of essentials.

Ms Hanson-Young also criticised the Government for secrecy over reports about a boat reportedly carrying Sri Lankan asylum seekers trying to get to Christmas Island.

There are conflicting reports about what has happened to those on board, with Prime Minister Tony Abbott and Mr Morrison refusing to release details.

However Mr Abbott said he thought Sri Lanka was a “peaceful country” where the “horrific civil war is well and truly over”.

Meanwhile SA Police say the responsibility for 12 asylum seeker children who ran away after two of their friends were removed from the community now lies with the Immigration Department.

A spokeswoman said police were in the process of filing the reports on the cases.

She said they would then be “managed in accordance with Immigration’s practices of absconded detainees”.

Mr Morrison said the children would be detained when found.

Uniting Communities on Thursday threw its support behind a push for Mr Morrison to be stripped of his responsibilities as guardian for unaccompanied asylum seeker children.

The Greens will introduce a Bill next week on the move, which is supported by Fairfax MP Clive Palmer and Australian Human Rights Commission President Gillian Triggs.