Aboriginal and Torres Strait Islanders were killed until at least 1930, often with police sanction, researchers say

Women perform a traditional dance at the commemoration of the 75th anniversary of the Coniston massacre at Brooks Soak north of Alice Springs in 2003. Photograph: Karen Michelmore/AAP

There have been as many as 500 massacres of Aboriginal and Torres Strait Islander peoples in Australia. And mass killings occurred well into the middle of the 20th century, researchers have said.

The disturbing revelations were released by the University of Newcastle on Friday as part of the second stage of its online massacre map, which now covers frontier violence that occurred from the arrival of the first fleet in 1788 to the colonisation of the Northern Territory, South Australia and remote Queensland up to 1930.

The map now details about 250 massacres that meet strict criteria of standards of proof, covering every state except Western Australia.

The estimated death toll from those incidents is about 6,200 Aboriginal and Torres Strait Islander peoples and fewer than 100 colonists, with an average of 25 Indigenous people killed in every massacre.