MELBOURNE (Reuters) - Australia will buy six U.S. Triton remotely piloted aircraft to beef up its maritime patrols, with the initial investment of A$1.4 billion ($1 billion) for the first drone, Prime Minister Malcolm Turnbull said on Tuesday.

The government said the Triton drones, made by Northrop Grumman Corp, would be used alongside P-8A Poseidon aircraft for long range operations and intelligence gathering, and would improve anti-submarine warfare and marine strike capability.

“This investment will protect our borders and make our region more secure,” Turnbull and Australia’s defence ministers said in a joint statement.

The total cost for the six drones, including facilities upgrades and support, will be A$6.9 billion, a person familiar with the transaction said.

Defence Industry Minister Christopher Pyne’s office declined to comment on the total cost of the aircraft, which can fly for up to 24 hours and have sensors that can view the surrounding area over 2,000 nautical miles (3,700 kms).

Australia will be working with the U.S. navy to develop, produce and sustain the MQ-4C Triton, the government said.

“Australia’s alliance with the U.S. is our most important defence relationship, underpinned by strong cooperation in defence industry and capability development,” the government said.

The first of the Triton aircraft is due to enter service in mid-2023. All six drones would be in operation by late 2025, based in South Australia.

The initial A$1.4 billion investment includes new facilities at two air force bases in Australia, ground control systems, support and training.