The head of BHP Billiton Andrew Mackenzie gets paid about 200 times as much as the average Australian, according to a latest research carried out by an Australian economist.

Mike Pottenger, Melbourne University economist, Wednesday told Australian newspaper The Age that back to 1980s the figure was just six or seven times as much.

Dr Pottenger said with the arrival of Paul Anderson as chief executive of BHP Billiton in 1998, there's a vertical jump. The then chief was paid more than 200 times average earnings.

Anderson's successors, Brian Gilbertson, Chip Goodyear, Marius Kloppers and Andrew Mackenzie, have all earned around 200 times the average. The trend has become the new normal, according to Dr Pottenger.

Mackenzie, who took charge of the company last month, is expected to earn about 25 percent less than his predecessor Kloppers, reflecting the hard times being felt across the mining sector.

Even though, the economist predicted the head can still earn a maximum of over 12 million U.S. dollars a year if BHP performs well.

Dr Pottenger noted BHP and other newly globalised companies all want to hire a chief executive who is better than the global median, saying that "The only way to do that is to bid up salaries."