Australia on Monday signed a 50 billion dollar (35.5 billion US dollar) contract with France to build a fleet of 12 “regionally superior’’ submarines.

Naval Group, a majority French state-owned defence and energy contractor, previously known as DCNS, was awarded the contract in 2016.

The contract was for the design of the submarines for the Australian Navy over proposals submitted by Japan and Germany’s ThyssenKrupp.

But the protracted negotiations over the final contract were fractious and even cast doubt over the deal in 2018 due to cost blowouts and production delays.

On Monday, Prime Minister, Scott Morrison and Defence Minister, Christopher Pyne met with French Armed Service Minister, Florence Parly in Canberra and signed the agreement to build the “regionally superior’ Attack class submarines.

Among other issues, the agreement governs the warranty lifespans and ownership of intellectual property.

The contract is Australia’s single largest infrastructure and development project, as well as the largest defence procurement.

Morrison hailed the “audacious plan’’ as “part of Australia’s biggest ever peacetime investment in defence.’’

“This means we are ensuring we are at the front of the pack when it comes to the latest naval vessels and firepower,” Morrison said.

“This agreement with Australia will see Naval Group transfer the ‘know-how’ and ‘know-why’ to Australia to become a sovereign submarine nation,” Naval Group Chairman and Chief Executive, Herve Guillou, said in a statement.

The group has built 100 of submarines for nine countries, he added.

The Australian submarines would be a variant of Naval Group’s non-nuclear Shortfin Barracuda with pump-jet propulsion.

This is quieter than conventional propellers and has more capabilities to stay underwater for longer periods and travel at greater distances.

U.S. defence contractor Lockheed Martin would design and fit the combat weapon systems.

According to Naval Group, work on the submarine construction yard in Adelaide has started.

The first of the fleet is expected to be ready sometime after 2030 and the final vessel after 2050.

In recent years, Australia has been trying to flex its military muscles – especially in the Asia-Pacific region, which has seen an intense struggle for influence between the U.S. and China.

It has committed to spending two per cent of gross domestic product on defence by 2020-21.

Australian has splurged more than 200 billion dollars in military investment and defence purchases, including six long-range spy drones from the U.S.

Others are 12 high-powered sea patrol vessels and 211 eight-wheel-drive “super tanks” from Germany as well as nine navy combat frigates from Britain. (dpa/NAN)