The discovery of human bones at the site of a Spitfire crash in which a New Zealand airman died in World War II has raised questions about whether he was alone as reported at the time.

A group of voluntary excavators found the remains at the site in Berwickshire, in the Scottish Borders, last weekend, UK's Daily Mirror reports.

Initial tests show the bones are human.

The RAF Spitfire crashed on January 16, 1943, killing 20-year-old pilot Sergeant Malcolm Robertson from the Royal New Zealand Air Force.

At the time, investigators said there was only one person on board the aircraft when it crashed shortly after embarking on a training flight from Drem air base, East Lothian, where 602 Squadron were based.

Sgt Robertson's remains were interred at Craigton Cemetery in Glasgow.

Lothian and Borders police and anthropologists from the Centre for Anatomy and Human Identification at Dundee University hoped to conclude their search on Sunday.

Detective Superintendent Lesley Boal said: "While the remains were recovered at the site we will not be able to confirm identity until specialist forensic testing has been carried out.

"Our primary objective is to safely and securely undertake a dignified recovery of any other human remains present at the previously excavated site."