A MASS grave uncovered outside Bundaberg earlier this week is an historically significant find that shines further light on a dark period of alleged slavery in 19th century Queensland.

Bundaberg Regional Council has confirmed ground radar technology identified 29 unmarked graves of South Sea Islanders on an old sugar cane plantation just east of Bundaberg yesterday morning.

The graves are in rows of 13, 10 and six, with one child buried among 28 adults.

Farmer and former federal Labor politician Brian Courtice - who last week appeared in The Courier Mail revealing plans to heritage-list his farm where scores of graves are believed to exist - said the confirmation was the first of its kind to occur in Queensland.

Council cemetery supervisor Gail Read, who found the graves, said there was no doubt they were those of South Sea Islander sugar plantation workers.

White settlers in the 19th century were not buried in unmarked graves, except in rare cases where suicide was involved, she said.

Ms Read said she knew there were many similar graves scattered throughout the district, but some elderly members of cane farming families were still reluctant to admit the graves existed on their properties.

While debate continues about whether South Sea Islanders were enslaved to work in sugarcane plantations, Mr Courtice says the graves are a crucial piece of evidence consistent with slavery.

"These people were buried without ceremony - they were often treated worse than livestock," he said. "They can't speak for themselves but I can speak for them - there will be a monument built to honour them."

Three representatives from the South Sea Islander community were at the Courtice farm yesterday afternoon, marking off the area where the graves were found with tape.

Mr Courtice has long argued there are similar grave sites across the state in sugar growing areas including Mackay and the Burdekin.

"But, to my knowledge, this is the first confirmed mass grave on an old sugar plantation," he said.

Mr Courtice has collected a large brief of evidence on South Sea Islander slavery, including verbal testimony taken during the 1990s from an elderly Bundaberg resident whose relatives had direct experience with the slave trade.

He said there was evidence to suggest Islanders working in the cane fields were often buried "where they fell", while others were executed for minor crimes.

Originally published as Slavery link in sugar plantation mass grave