Professor Ross Garnaut has blamed the Papua New Guinean's [PNG] immigration powers for his resignation from the board of a mining company based in PNG.
The country's biggest earner, Ok Tedi Mining lost Professor Garnaut as chairman after the nation's prime minister, Peter O'Neill, said in parliament that the Australian is not welcome in the country.
The professor of economics and author of the Garnaut Climate Change Review wrote a resignation letter outlining his reasons for departing, saying that he doesn't approve of government involvement with private enterprise.
He said: "It is undesirable for development in PNG that the government's use of its immigration powers should be seen as having been effective in forcing changes in the board of a major private company.
"For this reason, there was value in allowing some time for the prime minister to lift the ban should he be of a mind to do so. It is not possible for me to fulfil my responsibilities as chairman of this large, complex mining company for an indefinite period while the government is preventing me from travelling to PNG."
Professor Garnaut had previously travelled there up to eight times a year.
Prime minister O'Neill clarified his ban of the professor, saying that his immigration visa would be invalid until Australian-based BHP Billiton - one of the largest mining companies in the world - hands over control of the PNG Sustainable Development Program (PNGSDP) to the government and the people.
The PNGSDP is a trust that is administered by BHP and is designed to control Ok Tedi, which closed down its copper and gold mining ten years ago due to environmental concerns.
The trust sees a distribution of more than $100 million for development projects and has built up assets worth $1.36 billion. It currently owns 63.6 per cent of Ok Tedi Mining Ltd.
As a result, the PNG government owns the rest of the mining company.
Additionally, BHP now has to confirm its willingness to allow changes in ways that the trust operates - principally, allowing directors to be nominated by the board itself. These nominees can include government appointments.
November of last year saw a transition in power, with former PNG prime minister Mekere Morauta replacing the outgoing chairman of Ok Tedi Mining Ltd.
The former diplomat thanked the Australian economist for his contribution to the strengthening of the PNG economy.