This follows several months of discussions aided by the Australian National Contact Point.
A joint committee of stakeholders will be formed to oversee an independent assessment of the Panguna mine to identify and better understand actual and potential environmental and human rights impacts of the mine, which ceased operating in 1989.
The Panguna Mine Legacy Impact Assessment Committee will be established by the Autonomous Bougainville government and the parties to the AusNCP process including Rio Tinto, the Human Rights Law Centre and the community members the HRLC represents.
The committee will be chaired by an independent facilitator with representatives from the Papua New Guinea government, the Australian Securities Exchange-listed Bougainville Copper Limited, other landowners and community representatives invited to join.
Rio Tinto chief executive Jakob Stausholm said the agreement was an important first step.
"Operations at Panguna ceased in 1989 and we've not had access to the mine since that time," he said.
"Stakeholders have raised concerns about impacts to water, land and health and this process will provide all parties with a clearer understanding of these important matters, so that together we can consider the right way forward.
"We take this seriously and are committed to identifying and assessing any involvement we may have had in adverse impacts in line with our external human rights and environmental commitments and internal policies and standards."
The scope of the impact assessment, along with terms of reference for the committee, have been drafted by the parties to the AusNCP process.
The impact assessment is to be predominantly funded by Rio Tinto with BCL contributing separately. That is providing the broader stakeholders on the committee endorse the process and the proposed methodology of the impact assessment, the impact assessment can be safely completed, and an appropriate funding mechanism can be agreed.
The ABG confirmed its support for the process.
The committee will appoint a chairperson and an independent third-party company or consortium to complete the impact assessment.
Following the impact assessment Rio Tinto and the other parties to the AusNCP process will discuss the recommendations from the impact assessment and the remaining commitments sought by the communities.
Rio Tinto owned 53.83% of BCL, which operated the Panguna mine from 1972 to 1989, when operations were suspended due to an uprising against the mine and the subsequent civil war.
A peace agreement was signed in 2001 and Bougainville was given autonomy within PNG.
Rio Tinto transferred its majority stake in BCL to the ABG and the PNG government in 2016. That has enabled the ABG and PNG to each hold 36.4% of BCL.
Soul searching after the mine closed led Rio Tinto to change how it approached interactions with Traditional Owners of the land its operations were on and build a reputation for excellence in the area.
That reputation was damaged when Rio Tinto set off blasts in May 2020 in the Juukan Gorge that destroyed two 46,000 year old rock shelters considered sacred by the Traditional Owners of its Brockman mine.