A human leg found washed up on a beach on the New South Wales mid north coast on Tuesday has been identified as belonging to a spearfisherman who went missing 800km away.

Forensic police searched the serial number on a metal surgery plate found on the leg bone.

The plate identified the man as being Andrew Page, known as Drew, who vanished while free-diving in south-east Queensland.

A human leg that wash up on a New South Wales beach has been identitified as belonging to Andrew Page, 38, who went missing while spear-fishing off the Bundaberg coast in Queensland

Police investigate the scene at North Beach in Mylestom, south of Coffs Harbour where the leg washed ashore

The 38-year-old had been spear-fishing with friends off Elliot Beach, near Bundaberg, when he failed to resurface on November 23.

The captain of the boat he was on alerted authorities.

A five day sea search covering 350 nautical miles did not find any trace of him.

It is not known what happened to him - but sharks have been seen in the area.

His family have been informed that the remains found belong to Mr Page.

The grim discovery was made by a member of the public on North Beach in Mylestom, south of Coffs Harbour, at around two o'clock on December 17.

9News reported the remains included a femur, tibia and foot bones with a wetsuit bootie on the end.

No other human remains were found with the leg, which was washed up around one kilometre south of the North Beach Surf Life Saving Club.

Officers from the Coffs-Clarence Police District conducted the forensic examination on the leg and searched through missing persons reports.