The second-largest coal export port in New South Wales state is the defence department’s preferred site for a new east-coast submarine base, according to state broadcaster ABC.

Protesters carrying trade union banners and flags marched down the main street to voice their opposition to a base in the town of around 5,000 people 102km south of Sydney.

“I’m getting the sense of the renewable energy that’s in this community to keep coming out on the streets,” Greens Senator David Shoebridge, a prominent critic of AUKUS, told the crowd.

Estimates of the crowd ranged from 2,000 to 5,000, according to participants.

Australian defence minister Richard Marles said last month no decision had been made on a site for a new east coast submarine base.

Prime Minister Anthony Albanese has defended the submarine project after two former leaders criticised the deal over its cost, complexity and potential sovereignty issues.

The deal unveiled in March will see Australia purchase US Virginia-class submarines before joint British and Australian production of a new submarine class to be built in Australia by the early 2040s.