The Australian government has spent more than $4.5 million in its attempt to expel a Sri Lankan family of four, including two children born in Australia, from the country.

That figure, from September, is likely to have sharply escalated over the past four months as the married couple and their two young daughters have been held on an island far from the Australian mainland while they fight deportation.

The "Biloela family" — a Tamil family who spent years in the regional Queensland town of Biloela before being taken into immigration detention — attracted widespread protest and global media attention when the Australian government moved to deport them last August.

Since late August, Nadesalingam (known as Nades), Priya and their two Australian-born daughters, Kopika and Tharunicaa, have been the only people held on Christmas Island, an external territory of Australia.

Australian Border Force officers and employees from private contractor Serco took them from their home in Biloela in a dawn raid in March 2018, when their youngest daughter was seven months old. They spent over a year in detention in Melbourne, as they fought for protection visas, before coming nail-bitingly close to deportation in August 2019.

A last minute injunction issued by the Federal Court granted them temporary reprieve from deportation. A case looking at whether Tharunicaa, the younger daughter, is entitled to a protection visa is ongoing.

Biloela residents have called for the family to return to Queensland under the banner of the Home To Bilo campaign. Thousands have come out to protest their detention. But the government has held firm to its hard line: strong borders come first.

In the meantime, the government moved the family from Melbourne to Christmas Island, which sits more than 3,000km off the mainland’s west coast and is closer to Indonesia.

The family's detention has cost Australian taxpayers $2.5 million, according to new figures provided by the Department of Home Affairs to the Senate. The figures were current at Sept. 16, 2019 — which means they are likely to be much higher today.

The government has spent another $1.1 million on travel and transportation. The ongoing legal fight has cost the government at least $300,000. And a further $600,000 has gone to other expenses, including costs for staff who removed the family to Christmas Island.