Australians have roundly rejected greater rights for Indigenous citizens, scuppering plans to amend the country's 122-year-old constitution after a divisive and racially tinged referendum campaign.

With two-thirds of polling places reporting, 55% of voters had voted "no" to acknowledging Aboriginal and Torres Strait Islanders in the country's constitution for the first time.

The reforms would also have created a consultative body — a "Voice" to Parliament — to weigh in on laws that affect Indigenous communities and help address profound social and economic inequality.