It is believed that at least 240 of the men in the graves are British

They say there is "compelling" evidence that the bodies of up to 400 soldiers remain near the site of the Battle of Fromelles in northern France.

The discovery by Glasgow University's Centre for Battlefield Archaeology is the largest of its kind.

Australian, British, French and German authorities now have to decide whether to proceed with a mass exhumation.

'Draw attention'

It is estimated that 5,500 Australians and 2,000 British troops were killed or injured in the 1916 battle.

It was a terrible event that deserves to be remembered

Dr Tony Pollard

Although largely forgotten in Britain, in Australia the battle is believed to be nearly as important as that at Gallipoli.

A young Adolf Hitler served as a messenger on the German side.

Dr Tony Pollard, who led the team surveying the site, said it was important to keep alive the memory of those killed.

"To some extent, Fromelles was overshadowed by the Somme in Britain," he told the BBC News website.

"But it was a terrible event that deserves to be remembered.

"I hope that our work can draw attention to the thousands of men who were killed."

The site is believed to be the largest modern mass grave that was not the result of genocide.

Dr Pollard said German records indicated that between 60 and 160 of the men buried at the site were Australian, and the remainder British.

Using ground-penetrating radar and metal detectors, his team were able to pinpoint where they believe the graves were located.

The research was funded by the Australian government, but a multi-national group would have to be established if a decision were ever taken to exhume the bodies, Dr Pollard said.

'Gone astray'

The Battle of Fromelles is regarded by military historians as an unmitigated disaster.

Its plan was to divert German attention from the Somme by launching an assault on heavily-fortified positions in broad daylight.

The British withdrew and left the Australians to fight their way back through the German lines.

Hitler, then aged 27, served as a corporal with the 6th Bavarian reserve regiment in the battle.

Dr Pollard said: "It makes you think how the course of history could have changed if one bullet had gone astray."