ExxonMobil CEO Rex Tillerson

O'Neill said he was delighted Papua New Guinea would have a "very good and genuine friend" in the Donald Trump administration in one of the most important offices in the US Government.

"Our nation is privileged to know Mr Tillerson as a person with a genuine interest in economic development in our nation,” PM O’Neill said.

“In my discussions with Mr Tillerson on ExxonMobil's substantial and long term investment in Papua New Guinea's energy sector, I have been impressed by his understanding of the potential our nation holds.

Like Trump, Tillerson, 64, has no formal foreign policy experience, but has built close relationships with many world leaders by closing massive deals across Eurasia and the Middle East on behalf of the world's largest energy company.

Tillerson was originally a dark horse for the secretary of state nomination, but emerged from a lengthy public interview and vetting process that included better-known quantities like former New York Mayor Rudy Giuliani, 2012 GOP nominee Mitt Romney and Sen. Bob Corker, chairman of the Senate Foreign Relations committee.