Up to 600 bodies, including World War I diggers, could be buried in unmarked graves under Melbourne's La Trobe University, historians claim.

The land once belonged to Mont Park mental asylum, where hundreds of returned serviceman and civilian patients were admitted early last century.

Amateur historian Lambis Englezos told Seven News many returned serviceman who died at the hospital were not claimed by their families and were buried in pauper graves at the Bundoora site, near to Preston Cemetery.

"We believe quite firmly that our research indicates it (La Trobe University) is an abandoned burial site," he said.

"We believe there could be as many as 600 out there."

The university says it will use ground-penetrating radar to investigate whether a mass cemetery exists at the site.

Professor Christopher Mackie, the head of La Trobe's School of Humanities, told the ABC they are working out what to do if the graves are found.

"We want to do this properly. We've got to consult with a number of key stakeholders in this matter," he said.

"Clearly as far as the use of the land is concerned in the short term, there'll be nothing happening there."

Professor Mackie says ground-penetrating radar will be used to explore the area.

"What ultimately happens here will depend, I suppose, on what the ground-penetrating radar reveals, but also what the key stakeholders decide," he said.

Mr Englezos says if graves are found the site should be turned into a memorial garden featuring a plaque inscribed with soldiers' names and the words 'believed buried here'.

"Hopefully we will establish a process that will lead to restoration of dignity," he said.

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