Australia's multi-billion-dollar Joint Strike Fighter program has reached a new milestone with seven F-35A Lightning II aircraft arriving at RAAF Base Williamtown.

Defence Minister Linda Reynolds said the arrival brought the total number of F-35As at Williamtown to 13, with another five based at Luke Air Force Base in Arizona.

The F-35 program was on track to provide Australia with a fifth-generation aircraft at the forefront of air combat technology.

“This is the most advanced, multi-role stealth fighter in the world which will deliver next-generation capability benefits and provide a major boost to air combat capability," Senator Reynolds said.

The Australian Government has approved the next 24 aircraft – meaning all 72 Australian F-35A Lightning II aircraft are now locked in.

Defence has also signed on to an international deal known as the 'Block Buy Contract', valued in total at US$34 billion, which would deliver 45 of Australia’s F-35A Lightning II aircraft.

“The deal is great news for Australia with the unit price now 5 per cent below the estimate at Government approval in 2014,” Senator Reynolds said.