SYDNEY, Aug 30, 2025 (BSS/AFP) - Australia has announced an agreement with the tiny Pacific nation Nauru enabling it to send hundreds of immigrants to the barren island.

The deal affects more than 220 immigrants in Australia, including some convicted of serious crimes.

Home Affairs Minister Tony Burke signed the memorandum of understanding on a visit to Nauru, the government said in a statement Friday.

"It contains undertakings for the proper treatment and long-term residence of people who have no legal right to stay in Australia, to be received in Nauru," it said.

"Australia will provide funding to underpin this arrangement and support Nauru's long-term economic resilience."

Canberra did not provide financial details.

The Sydney Morning Herald said, however, that Australia would pay Nauru Aus$408 million (US$267 million) and about Aus$70 million a year thereafter under the deal.

"Anyone who doesn't have a valid visa should leave the country," Burke said in a statement.

"This is a fundamental element of a functioning visa system."

Australia's government has been searching for a way to deal with immigrants who have no other country to go to when their visas are cancelled.

The High Court ruled in 2023 that indefinite detention was "unlawful" if deportation was not an option, leading to the release of 220 people.

The number of immigrants in that situation now numbers more than 350, according to the Sydney Morning Herald.

In February, Australia paid an undisclosed sum for Nauru to accept three immigrants convicted of violent offences, though legal challenges have reportedly stalled their transfer.

Last year, Australia and Nauru signed an agreement spanning maritime security, defence and policing.

Nauru, population 12,500, is one of the world's smallest countries with a mainland measuring just 20 square kilometres (7.7 square miles).

It is considered especially vulnerable to climate change and has high rates of unemployment and health issues, a recent World Bank assessment said.

Unusually pure phosphate deposits -- a key ingredient in fertiliser -- once made Nauru one of the wealthiest places, per capita, on the planet.

But those supplies have long dried up, and researchers today estimate 80 percent of Nauru has been rendered uninhabitable by mining.