Research commissioned by the Netherlands has suggested that a key 1969 vote on the future of the Indonesian province of Papua was "a sham" orchestrated by Jakarta.
The study, "An Act of Free Choice," was published by the Dutch author Pieter Drooglever.
The report finds the vote was followed by decades of abuse at the hands of the Indonesian military.
Indonesia first invaded the former Dutch colony of Western Papua New Guinea in 1962.
A year later it was allowed to administer the area under United Nations rule, with the region promised a popular vote on its sovereignty.
But it was not until 1969 that 1-thousand and 22 tribal chiefs unanimously voted to become part of Indonesia on behalf of a population of 700,000.
Mr Drooglever says UN observers were turned away from the voting sites and the poll was tainted by bribery and intimidation of the chiefs.