The Muruguppan family were later moved from Biloela in Queensland to immigration detention on Christmas Island and are now at the centre of a political debate over border security.

One of the family's two Australian-born daughters, four-year-old Tharnicaa, was last week flown to Perth for medical treatment after developing pneumonia and sepsis.

"There is considerable national, public interest and support for this family to be allowed to remain in Australia," the Temora resident's letter to Mr McCormack stated in January 11, 2019.

The resident had asked Mr McCormack to express support for the family but when he forwarded the letter to then Immigration Minister David Coleman on January 18, the MP and Deputy PM asked only for a response.

"We live in a democracy where anyone can freely express their views and I will always seek to provide a response to constituents who write to me raising matters which concern them," Mr McCormack said yesterday in response to questions about the letter.

Some of Mr McCormack's fellow Coalition MPs went further in letters to Mr Coleman in early 2019, with Tony Abbott stating in a handwritten postscript that the family could have a case to stay in Australia.

Barnaby Joyce told Mr Coleman he would be "grateful if consideration could be given to the concerns and points raised" by one of his constituents.

Tharnicaa's parents, Priya and Nadesalingam, arrived by boat in Australia in 2012 and 2013 after fleeing violence between the Sri Lankan government and their Tamil ethnic group.

Mr McCormack, as acting Prime Minister, kept a hard line on the issue on Monday after multiple Liberal MPs spoke out in favour of releasing the family from detention.

On Monday, Mr McCormack warned that granting an exemption in this case risked a return of people smuggling and deaths at sea after the government "stopped the boats".

In other news

The existence of the letters were revealed in a Federal Court judgment in February and were released last week after a Freedom of Information request to Home Affairs.

Labor leader Anthony Albanese has called on Home Affairs Minister Karen Andrews to release the family.

Mr McCormack said Immigration Minister Alex Hawke would make a decision on the family's case this week and some media reports have claimed they will be released within days.

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