Mass grave discovered in Osaka, Japan, with bodies buried in circular holes

Human bones buried in holes at the south section of the 'Umeda Grave' burial site, in Osaka, western Japan. Photo / AP

An ancient and eerie mass grave has been uncovered in Japan, with archaeologists uncovering more than 1500 bodies squashed into circular holes.

The graveyard was found in the Japanese city of Osaka, however archaeologists have been painstakingly excavating the area since 1991.

The mass grave dates back to Japan's Edo period, stretching from the start of the 1600s to the mid-1800s.

The mass grave dates back to Japan's Edo period, stretching from the start of the 1600s to the mid-1800s. Photo / AP

In a statement, the City of Osaka said the Osaka City Board of Education and the Osaka City Cultural Heritage Association had been working on the Ofuka-cho ruins since September 1991.

The City of Osaka said it had uncovered more than 1500 burial bones including those of humans and animals.

"In addition to humans, animals are also buried in the cemetery, with more than four piglets in the northern part of the cemetery and two horses in the southern part. A cat bone contained in a skeleton has also been found," the council said.

"We were able to clarify the concrete appearance of the 'Umeda Tomb' that was run from Edo to the Meiji era.

"The 'Osaka Nana Grave' was an important part of knowing the development of the city Osaka and the faith of the common people.

The excavated remains, including human bones, are being sorted and analysed. Photo / AP

"Most of the surveyed areas have already been backfilled, but we are still investigating the southwestern part of the cemetery."

Some pottery was found in the grave also. Photo / AP

The excavated remains, including human bones, are being sorted and analysed.

The Osaka gravesite is next to a major train station in the busy Japanese city and was uncovered during early construction work for a skyscraper.

The developers said plans for the building will likely go ahead, with the skyscraper being built on top of the burial ground.

The bones are already in the process of being moved and it's believed the bodies were likely those of poor people due to the lack of expensive goods in the graves.