Australia's government announced on Saturday that it had signed a treaty with Britain to strengthen collaboration for the next 50 years under the AUKUS nuclear submarine partnership.

The AUKUS agreement, signed by Australia, Britain and the United States in 2021, aimed to provide Australia with nuclear-powered attack submarines from the next decade to counter China's ambitions in the Indo-Pacific. Earlier this year, the administration of U.S. President Donald Trump announced a formal review of the deal.

Defence Minister Richard Marles said in a statement that the bilateral treaty had been signed with Britain's Defence Secretary John Healey on Saturday after a meeting in the city of Geelong in Victoria state.

"The Geelong Treaty will facilitate wide-ranging cooperation on the design, construction, operation, maintenance, and disposal of our SSN-AUKUS submarines," the statement said.

The treaty was described as a "pledge for the next 50 years of UK-Australian bilateral defence cooperation under AUKUS Pillar I", and it added that it was built on the "firm basis" of trilateral AUKUS cooperation.

Britain's defence ministry said earlier this week that the bilateral treaty would support both nations' submarine programmes, expected to be worth up to 20 billion pounds ($27.1 billion) to Britain in exports over the next 25 years.

AUKUS was Australia's largest defence project, with Canberra committing A$368 billion over three decades to the programme, which also included billions of dollars of investment in the U.S. industrial base.

Australia, which this month paid A$800 million to the U.S. as the second instalment under AUKUS, said it remained confident the deal would proceed.

The defence and foreign ministers of Australia and Britain held talks on Friday in Sydney to boost cooperation, coinciding with Australia's biggest war games.

As many as 40,000 troops from 19 nations were participating in the Talisman Sabre exercises being held from July 13 to August 4, which Australia's military described as a rehearsal for joint warfare to maintain Indo-Pacific stability.

Britain had increased its participation in the exercise co-hosted by Australia and the United States, with the aircraft carrier HMS Prince of Wales taking part this year.