The federal government's failed bid to return 157 asylum seekers to India cost taxpayers more than $12 million, as passengers were held at sea for nearly a month before being brought to the Australian mainland.
A cost analysis by Fairfax Media found the money was outlaid by the government to ensure the Sri Lankan nationals did not arrive on Australian shores to challenge Immigration Minister Scott Morrison's resolve of "stopping the boats".
The analysis, based largely on Senate Estimates figures, includes the daily running cost of the navy frigate HMAS Perth which first intercepted the boat after it left India, and the customs vessel Ocean Protector where the asylum seekers were kept on board for 29 days.
Also included are accommodation costs at Cocos Island for 14 immigration officials plus $600,000 in chartered flights to take the asylum seekers from there to the Curtin detention centre.
There were also estimated legal costs of over $136,000 associated with the High Court challenge launched against the government plus the costs of Mr Morrison's last-minute trip to New Delhi where he presented Indian officials with two cricket bats worth $695 each.
Human Rights Watch said the cost was "outrageous and unnecessary" and Greens immigration spokeswoman Sarah Hanson-Young said the cost could have been entirely avoided if the asylum seekers had been taken straight to Christmas Island.