Three people have died, including two volunteer marine rescuers, after a yacht sank and a rescue boat rolled in choppy conditions off Australia's New South Wales (NSW) coast.

Emergency services were called at 18:15 local time on Monday after a member of the public reported a yacht in trouble off the break wall in South Ballina, a popular coastal destination close to the NSW and Queensland border.

A Marine Rescue NSW crew rushed to the scene but their vessel capsized in rough conditions as it crossed the Ballina Bar, police said. Two rescuers, aged 78 and 62, died.

Four people made it to shore with minor injures and a search was called off on Tuesday morning after everyone was accounted for.

The body of a third man, believed to be aged in his 50s, was found on the sand nearby and is yet to be formally identified.